Faculty Profiles - ISHIKAWA, Yoshiharu

Papers - ISHIKAWA, Yoshiharu

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Evaluation of Signature Files as Set Access Facilities in OODBs Reviewed

Yoshiharu Ishikawa, Hiroyuki Kitagawa, and Nobuo Ohbo

Proceedings of the 1993 ACM SIGMOD International Conference on Management of Data (SIGMOD '93) page： 247-256 1993.5

Authorship：Lead author Language：English

Object-oriented database systems (OODBs) need efficient support for manipulation of complex objects. In particular, support of queries involving evaluations of set predicates is often required in handling complex objects. In this paper, we propose a scheme to apply signature file techniques, which were originally invented for text retrieval, to the support of set value accesses, and quantitatively evaluate their potential capabilities. Two signature file organizations, the sequential signature file and the bit-sliced signature file, are considered and their performance is compared with that of the nested index for queries involving the set inclusion operator (subseteq). We develop a detailed cost model and present analytical results clarifying their retrieval, storage, and update costs. Our analysis shows that the bit-sliced signature file is a very promising set access facility in OODBs.

Estimation of False Drops in Set-valued Objects Retrieval with Signature Files Reviewed

Hiroyuki Kitagawa, Yoshiaki Fukushima, Yoshiharu Ishikawa, and Nobuo Ohbo

Proceedings of the Fourth International Conference on Foundations of Data Organization and Algorithms (FODO '93) page： 146-163 1993.10

Language：English

Advanced database systems have to support complex data structures as treated in object-oriented data models and nested relational data models. In particular, efficient processing of set-valued object retrieval (simply, set retrieval) is indispensable for such systems. In the previous paper [6], we proposed the use of signature files as efficient set retrieval facilities and showed their potential capabilities based on a disk page access cost model. Retrieval with signature files is always accompanied by mismatches called false drops, and it is very important in designing signature files to properly control the false drops.
In this paper, we present an in-depth study of false drops in set retrieval with signature files. We derive formulas estimating false drops in four types of set retrieval based on the has-subset, is-subset, has-intersection, and is-equal relationships. Then we evaluate their validity by computer simulations. Simulation study is also done to investigate false drops in practically probable more complex situations.

Analysis of Indexing Schemes to Support Set Retrieval of Nested Objects Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

Proceedings of the International Symposium on Advanced Database Technologies and Their Integration (ADTI '94) page： 55-62 1994.10

Authorship：Lead author Language：English

Efficient retrieval of nested objects is an important issue in
advanced database systems. So far, many indexing methods for nested objects are proposed. However, they do
not consider retrieval of nested objects based on the set
comparison operators such as subseteq and supseteq. In this paper, we
propose four set access facilities for nested objects and compare their performance in terms of retrieval cost, storage
cost, and update cost. Our analysis shows that a combination of the signature file method and the nested index is
very promising for set retrieval of nested objects

Cost Evaluation of Set-valued Object Retrieval with Signature Files Reviewed

Yoshiharu Ishikawa, Hiroyuki Kitagawa, and Nobuo Ohbo

Journal of IPSJ Vol. 36 ( 2 ) page： 383-395 1995.2

Design and Performance Analysis of Indexing Schemes for Set Retrieval of Nested Objects Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

IEICE Transactions on Information and Systems Vol. E78-D ( 11 ) page： 1424-1432 1995.11

Language：English Publishing type：Research paper (scientific journal)

Efficient retrieval of nested objects is an important issue in advanced database systems. So far, a number of indexing methods for nested objects have been proposed. However, they do not consider retrieval of nested objects based on the set comparison operators such as subseteq and supseteq. Previouly, we proposed four set access facilities for nested objects and compared their performance in terms of retrieval cost, storage cost, and update cost. In this paper, we extend the study and present refined algorithms and cost formulas applicable to more generalized situations. Our cost models and analysis not only contribute to the study of set-valued retrieval but also to cost estimation of various indexing methods for nested objects in general.

Design and Evaluation of Signature File Organization Incorporating Vertical and Horizontal Decomposition Schemes Reviewed

Hiroyuki Kitagawa, Noriyasu Watanabe, and Yoshiharu Ishikawa

Proceedings of the Seventh International Conference on Database and Expert Systems Applications (DEXA'96) page： 875-888 1996.9

Language：English

Signature files are known as promising facilities to speed up access to large information repositories in database and information retrieval systems. This paper presents a new signature file organization method, named Partitioned Frame-Sliced Signature File (P-FSSF), and studies its performance. P-FSSF incorporates both vertical and horizontal decomposition schemes to reduce page accesses required to look up signatures. In addition, P-FSSF is flexible enough to have its concrete organization tuned to real application environments. We develop formulas to estimate the retrieval cost of P-FSSF in the context of the general set-valued object retrieval. Also, formulas to tell the update and storage costs are derived. Then, the processing cost of P-FSSF is shown to be lower than the other existing signature file organizations in general. We also show that Partitioned Bit-Sliced Signature File (P-BSSF), which is a special case of P-FSSF, is appropriate organization in most probable cases through the study of the optimal parameter values for P-FSSF.

SignatureCache: An Efficient Access Structure for Distributed Mediated Environments Reviewed

Yoshiharu Ishikawa and Shunsuke Uemura

Proceedings of the International Symposium on Cooperative Database Systems for Advanced Applications (CODAS '96) page： 538-541 1996.12

Language：English

To integrate distributed heterogeneous information sources in networked environments, we need efficient facilities to access such information. In this paper, we propose a method called SignatureCache to enable clients to access distributed sources in an efficient manner. The method is based on signature files, a popular indexing method in text retrieval. In our framework, a mediator extracts textual information from each source and generates a signatur---a compact representation of the extracted information. Generated signatures are collected by the mediator and accumulated into a signature file. Each client of the mediator replicates a part of signatures in the signature file during query execution time. The cached signatures can be considered as a special kind of signature file, thus we can utilize them for efficient index lookup at later time. In query processing, we can make use of subsumption relationship between queries and the semantic descriptions for cached signatures to determine whether the required signature entries are locally available or not.

A Wrapping Architecture for IR Systems to Mediate External Structured Document Sources Reviewed

Yoshiharu Ishikawa, Takehiro Furudate, and Shunsuke Uemura

Proceedings of the Fifth International Conference on Database Systems for Advanced Applications (DASFAA '97) page： 431-440 1997.4

Authorship：Lead author Language：English

With the growth of digital libraries and electronic publishing, many structured document sources are appearing and their effective mediation is an important research topic. In this paper, we propose a wrapping architecture for externally maintained structured document sources. Our wrapping target is information retrieval systems (IRSs) that provide access to structured documents. We describe a wrapper construction method for such IRSs with limited functionality. The constructed wrapper enhances retrieval facilities of the underlying IRS and provides an object database view to the mediator. We focus on determining whether the underlying IRS can support a given query. Then we discuss some research issues related to our wrapping architecture.

False Drop Analysis of Set Retrieval with Signature Files Reviewed

Hiroyuki Kitagawa and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E80-D ( 6 ) page： 653-664 1997.6

Language：English Publishing type：Research paper (scientific journal)

Modern database systems have to support complex data objects, which appear in advanced data models such as object-oriented data models and nested relational data models. Set-valued objects are basic constructs to build complex structures in those models. Therefore, efficient processing of set-valued object retrieval (simply, set retrieval) is an important feature required of advanced database systems. Our previous work proposed a basic scheme to apply superimposed coded signature files to set retrieval and showed its potential advantages over the B-tree index based approach using a performance analysis model. Retrieval with signature files is always accompanied by mismatches called false drops, and proper control of the false drops is indispensable in the signature file design. This study intensively analyzes the false drops in set retrieval with signature files. First, schemes to use signature files are presented to process set retrieval involving "has-subset," "is-subset," "has-intersection," and "is-equal" predicates, and generic formulas estimating the false drops are derived. Then, three sets of concrete formulas are derived in three ways to estimate the false drops in the four types of set retrieval. Finally, their estimates are validated with computer simulations, and advantages and disadvantages of each set of the false drop estimation formulas are discussed. The analysis shows that proper choice of estimation formulas gives quite accurate estimates of the false drops in set retrieval with signature files.

MindReader: Querying Databases through Multiple Examples Reviewed

Yoshiharu Ishikawa, Ravishankar Subramanya, and Christos Faloutsos

Proceedings of the 24th International Conference on Very Large Data Bases (VLDB '98) page： 218-227 1998.8

Authorship：Lead author Language：English

Users often can not easily express their queries. For example, in a multimedia/image by content setting, the user might want photographs with sunsets; in current systems, like QBIC, the user has to give a sample query, andto specify the relative importance of color, shape and texture. Even worse, the user might want correlations between attributes, like, for example, in a traditional, medical record database, a medical researcher might wantto find "mildly overweight patients", where the implied query would be "weight/height ~ 4 lb/inch".

Our goal is to provide a user-friendly, but theoretically solid method, tohandle such queries. We allow the user to give several examples, and, optionally, their 'goodness' scores, and we propose a novel method to "guess" which attributes are important, which correlations are important, and withwhat weight.

Our contributions are twofold: (a) we formalize the problem as a minimization problem and show how to solve for the optimal solution, completely avoiding the ad-hoc heuristics of the past. (b) Moreover, we are the first that can handle 'diagonal' queries (like the 'overweight' query above). Experiments on synthetic and real datasets show that our method estimates quickly and accurately the 'hidden' distance function in the user's mind.

A Semantic Caching Method Based on Linear Constraints Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

Proceedings of the 1999 International Symposium on Database Applications in Non-Traditional Environments (DANTE'99) page： 133-140 1999.11

Authorship：Lead author Language：English

Because performance is a crucial issue in database systems, data caching techniques have been studied in database research field, especially in client-server databases and distributed databases. Recently, the idea of semantic caching has been proposed. The approach uses semantic information to describe cached data items so that it tries to exploit not only temporal locality but also semantic locality to improve query response time. In this paper, we propose linear constraint-based semantic caching as a new approach, we describe the semantic information about the cached relational tuples as compact constraint tuples. The focus in this paper is the representation method of cache information and the cache examination algorithm.

A Rule-oriented Architecture to Incorporate Dissemination-based Information Delivery into Information Integration Environments Reviewed

Hironori Mizuguchi, Hiroyuki Kitagawa, Yoshiharu Ishikawa, and Atsuyuki Morishima

Proceedings of East-European Conference on Advances in Databases and Information Systems Held Jointly with International Conference on Database Systems for Advanced Applications (ADBIS-DASFAA 2000) page： 185-199 2000.9

Language：English

Integration of heterogeneous information sources has been one of important research issues in recent advanced application environments. Today, various types of information sources are available. Dissemination-based information delivery services that autonomously deliver information from the server sites to users are among the useful and promising information sources. In this paper, we present incorporation of dissemination-based information delivery into information integration environments. The integration here has two goals: (1) Users can utilize dissemination-based information services as other information sources such as databases and the Web. Namely, they can be sources of information integration. (2) Users can obtain integrated information through dissemination-based delivery. We explain this requirement can be met by a combination of an information integration engine and event-driven rule processing scheme. We also explain prototype system development.

X2QL: An eXtensible XML Query Language Supporting User-defined Foreign Functions Reviewed

Norihide Shinagawa, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Language：English

With the recent and rapid advance of the Internet, management of structured documents such as XML documents and their databases has become more and more important. A number of query languages for XML documents have been proposed up to the present. Some of them enable tag-based powerful document structure manipulation. However, their contents processing capability is very limited. Here, the contents processing implies the similarity-based selection, ranking, summary generation, topic extraction, and so on, as well as simple string-based pattern matching. In this paper, we propose an extensible XML query language X2QL, which features inclusion of user-defined foreign functions to process document contents in the context of XML-QL-based document structure manipulation. This feature makes it possible to integrate application-oriented high-level contents processing facilities into querying documents. We also describe an implementation of an X2QL query processing systemon top of XSLT processors.

Integration of Spatial Information Sources Based on Source Description Framework Reviewed

Yoshiharu Ishikawa, Gihyong Ryu, and Hiroyuki Kitagawa

Proceedings of the Seventh International Conference on Database Systems for Advanced Applications (DASFAA 2001) page： 160-161 2001.4

Authorship：Lead author Language：English

Recent progress of digital cartography and Internet technologies
enabled new types of services on the network such
as search engines that provide information within some specific
geographic areas and retrieval services which allow
map-oriented query interfaces. We call such services spatial
information sources. In this paper, we propose a framework
to integrate heterogeneous spatial information sources
to provide an integrated view to users. Our main focus is
heterogeneity of spatial information sources―since existing
spatial information sources differ in their contents and
query capabilities, integration of such sources requires an
appropriate framework to describe their contents and query
capabilities. In this paper, we show such a description
framework and illustrate query processing strategies that
utilize source descriptions of spatial information sources.

Algebraic Service Specification and Rule Generation for Integrating Multiple Dissemination-Based Information Systems Reviewed

Hiroyuki Kitagawa, Tomoyuki Kajino, Yoshiharu Ishikawa

Proceedings of the Seventh International Conference on Database Systems for Advanced Applications (DASFAA 2001) page： 344-351 2001.4

Language：English

Integration of heterogeneous information sources has
been one of important data engineering research issues.
Various types of information sources are available today.
They include dissemination-based information sources,
which actively and autonomously deliver information
from server sites to users. We have been developing a
mediator/wrapper-based information integration system, in
which we employ ECA rules to enable users to define new
information delivery services integrating multiple existing
dissemination-based information sources. However, it is
not easy for users to directly specify ECA rules and to verify
them. In this paper, we propose a scheme to specify new
information delivery services using the framework of the
relational algebra. We discuss some important properties
of the specification, and show how we can derive ECA rules
to implement the delivery services.

Querying Geographic Data in XML via Extensible XML Query Language X2QL Reviewed

Norihide Shinagawa, Takayuki Nagai, Hiroyuki Kitagawa, Yoshiharu Ishikawa

Proceedings of Symposium on ASIA GIS 2001 page： (CD-ROM publishing, no page no) 2001.6

Language：English

XML has attracted a great deal of attention as standard data exchange format, and XML representing geographic information such as G-XML has been developed. In near future, geographic data written in XML will be exchanged through the Internet. Therefore, it will become a very important issue to efficiently query geographic data in XML. To query geographic data in XML, spatial operations such as distance calculation and spatial containment test need be provided in query languages. However, in general, XML query languages do not support such spatial operations. This paper illustrates G-XML data can be queried via eXtensible XML Query Language X2QL, which has been developed by our research group. X2QL features inclusion of user-defined foreign functions to introduce application-oriented processing capability. Thus, we can utilize various spatial operations in X²QL as appropriate foreign functions. This paper also describes the development of a prototpye X2QL query processing system.

An On-Line Document Clustering Method Based on Forgetting Factors Reviewed

Yoshiharu Ishikawa, Yibing Chen, and Hiroyuki Kitagawa

Proceedings of the 5th European Conference on Research and Advanced Technology for Digital Libraries (ECDL 2001) page： 332-339 2001.9

Authorship：Lead author Language：English

With the rapid development of on-line information services, information technologies for on-line information processing have been receiving much attention recently. Clustering plays important roles in various on-line applications such as extraction of useful information from news feeding services and selection of relevant documents from the incoming scientific articles in digital libraries. In on-line environments, users generally have interests on newer documents than older ones and have no interests on obsolete old documents. Based on this observation, we propose an on-line document clustering method F2ICM ( Forgetting-Factor-based Incremental Clustering Method) that incorporates the notion of a forgetting factor to calculate document similarities. The idea is that every document gradually losses its weight (or memory) as time passes according to this factor. Since F2ICM generates clusters using a document similarity measure based on the forgetting factor, newer documents have much effects on the resulting cluster structure than older ones. In this paper, we present the fundamental idea of the F2ICM method and describe its details such as the similarity measure and the clustering algorithm. Also, we show an efficient incremental statistics maintenance method of F2ICM which is indispensable for on-line dynamic environments. Keywords: clustering, on-line information processing, incremental algorithms, forgetting factors

Source Description-Based Approach for the Modeling of Spatial Information Integration Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

Proceedings of the 20th International Conference on Conceptual Modeling (ER 2001) page： 41-55 2001.11

Authorship：Lead author Language：English

Rapid development of information technology such as mobile terminals and GPS systems enabled information services that provide location-oriented information based on users' positions. In this paper, we propose an approach for the modeling of information integration applications that incorporate spatial information sources in addition to conventional information sources to provide appropriate location-oriented information to users. First, we present our approach to the modeling of spatial information sources based on the source description framework. It provides a way to represent the content and the query capability of a spatial information source in a descriptive manner. Then we show a query processing scheme that finds a combination of information sources to respond to given queries and to evaluate them efficiently.

Integration of Multiple Dissemination-Based Information Sources Using Source Data Arrival Properties Reviewed

Yousuke Watanabe, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Proceedings of the 2nd International Conference on Web Information Systems Engineering (WISE 2001) page： 21-30 2001.12

Language：English

The integration of heterogeneous information sources is an important data engineering research issue. Various types of information sources are available today. They include dissemination-based information sources, which actively and autonomously deliver information from servers to users. We are developing a mediator/wrapper-based information integration system in which we employ ECA rules to define new information delivery channels, integrating multiple existing dissemination-based information sources. ECA rules in this system are derived from integration requirement specifications based on relational algebra provided by users. Dissemination-based information sources usually have data arrival properties, such as an information delivery schedule. Using the data arrival properties of underlying information sources, the system can derive more appropriate ECA rules and check the consistency of requirements more accurately. This paper proposes an extended scheme to process information integration requirements using source data arrival properties of dissemination-based information sources.

Specification of Dissemination Services and Derivation of ECA Rules in Dissemination-Based Information Integration Environments Reviewed

Tomoyuki Kajino, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J85-DI ( 1 ) page： 40-52 2002.1

Language：Japanese Publishing type：Research paper (scientific journal)

Integration of heterogeneous information sources has been one of important research in recent advanced network environments. In these days, various types of information sources are available. Dissemination-baesd information sources that actively deliver information from server sites to users are important information sources. In our research group, a dissemination-based information integration system that uses ECA rules to process dissemination-based information sources has been built to incorporate delivered information in a flexible manner. However, the users of the system have to specify and verify ECA rules by themselves. In this paper, we present a framework to specify dissemination services declaratively, and to derive ECA rules automatically.

Processing Queries Including User - defined Foreign Functions on XML Views over Relational Databases Reviewed

Jun Kawada, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

IPSJ Transactions on Databases Vol. 43 ( SIG 12(TOD 16) ) page： 16-37 2002.12

Language：Japanese Publishing type：Research paper (scientific journal)

XML views over RDBs and to allow users to access data with XML query languages such as XQuery.The query processing is done effciently by making the best of the querying power of RDBMSs.Namely,XML queries are translated into SQL queries and tagging operations, which are processed by the RDBMSs and, middleware,respectively.In some XML query languages including XQuery,use of user-de ?ned foreign functions is enabled or planned as an extension feature to cope with domain dependent semantics.Foreign functions are de ?ned for XML fragments,and their implementations are often given by codes in a general programming language.The existing query processing schemes on XML views do not consider cases where foreign functions are included in XML queries.In this paper,we propose extended schemes to process XML queries in such cases.In the proposed schemes,the middleware takes care of processing foreign functions as well as tagging operations.Therefore,the proposed schemes are applicable to XML views on commonly available RDBMSs.Three types of query processing schemes are proposed,and their performance is studied with experiments.

Continual Neighborhood Tracking for Moving Objects Using Adaptive Distances Reviewed

Yoshiharu Ishikawa, Hiroyuki Kitagawa, and Tooru Kawashima

Proceedings of the International Database Engineering and Application Symposium (IDEAS'02) page： 54-63 2002.7

Authorship：Lead author Language：English

Based on the recent progress of digital cartography, global positioning systems (GPSs), and hand-held devices, there are growing needs of technology that provides neighborhood information to moving objects according to their locations and trajectories. In this paper, we propose spatial query generation models that take account of the current position and the past/future trajectories of a moving object to provide appropriate neighborhood information to it. For this purpose, we introduce an influence model of trajectory points and derive neighborhood query generation models using adaptive ellipsoid distances. We describe query processing strategies for these query generation models and show incremental query update procedures to support continual query facilities with low processing cost. Finally, we present experimental results to show the effectiveness of our approach.

配信型情報源統合環境における統合演算の共有 Reviewed

渡辺陽介, 北川博之, 石川佳治

情報処理学会・電子情報通信学会情報・システムソサイエティ共催第1回情報科学技術フォーラム (FIT2002) 情報技術レターズ Vol. 1 page： 65-66 2002.9

Transforming XPath Queries for Bottom-Up Query Processing Reviewed

Yoshiharu Ishikawa, Takaaki Nagai, and Hiroyuki Kitagawa

Proceedings of the IASTED Interanational Conference on Information Systems and Databases (ISDB 2002) page： 210-215 2002.9

Authorship：Lead author Language：English

The widespreading of XML as a content-description language
on the Web requires advanced processing and
management techniques for huge XML databases. XPath
is a standard language for extracting the specified elements
from XML documents, and its efficient support
is one of the key issues in the current XML database
technology. In this paper, we propose an XPath query
transformation method for the efficient query processing.
It transforms top-down, navigation-based XPath queries
into equivalent bottom-up query plans by using schema
information. Based on this technique, we can achieve efficient
set-oriented processing of XPath queries with the
support of index mechanisms.

VIDI: Visual Specification for Integration of Distributed Dissemination-based Information Sources Reviewed

Yousuke Watanabe, Yoshinori Okamoto, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Proceedings of the IASTED International Conference on Network, Parallel and Distributed Processing, and Applications (NPDPA 2002) page： 217-222 2002.9

Integration of Multiple Dissemination-Based Information Sources Using Source Data Arrival Properties and Validation of Integration Requirements Reviewed

Yousuke Watanabe, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IEICE Transactions on Inforamtion and Systems (Japanese Edition) Vol. J85-DI ( 12 ) page： 1126-1141 2002.12

Processing XML View Queries Including User-defined Foreign Functions on Relational Databases Reviewed

Yoshiharu Ishikawa, Jun Kawada, and Hiroyuki Kitagawa

Proceedings of the 3rd International Conference on Web Information Systems Engineering (WISE 2002) page： 225-236 2002.12

Authorship：Lead author Language：English

With the increased popularity of XML, XML publishing of RDBs has been attracting a lot of research interests. One of typical approaches is to use a middleware system to render XML views over RDBs and to allow users to access data with XML query languages such as XQuery. The query processing is done efficiently by making the best of the querying power of RDBMSs. Namely, XML queries are translated into SQL queries and tagging operations, which are processed by the RDBMSs and middleware, respectively. In some XML query languages including XQuery, use of user-defined foreign functions is enabled or planned as an extension feature to cope with domain dependent semantics. Foreign functions are defined for XML fragments, and their implementations are often given by codes in a general programming language. The existing query processing schemes on XML views do not consider cases where foreign functions are included in XML queries. In this paper, we propose extended schemes to process XML queries in such cases. In the proposed schemes, the middleware takes care of processing foreign functions as well as tagging operations. Therefore, the proposed schemes are applicable to XML views on commonly available RDBMSs. Three types of query processing schemes are proposed, and their performance is studied with experiments.

ignature-based Object Retrieval in Peer-to-Peer Environments Reviewed

Ryo Matsushita, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IPSJ Transactions on Databases Vol. 44 ( SIG 12(TOD 19) ) page： 139-149 2003.9

Language：Japanese Publishing type：Research paper (scientific journal)

Peer-to-peer (P2P) technology has attracted a lot of attention in recent years. Efficient object retrieval is an important research issue in P2P environments, especially in those without centralized global indices. Although a number of hash-based basic object retrieval schemes are known to alleviate the problem, they cannot provide flexible feature-based object search. In this paper, we propose a novel object retrieval method using distributed frame sliced signatures, and evaluate its effectiveness with simulation experiments.

An Efficient Mobility Statistics Extracting Method for Indexed Spatio-Temporal Datasets Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 1 ) page： 27-30 2003.5

Language：Japanese Publishing type：Research paper (scientific journal)

With the recent progress of spatial information technologies
and mobile computing technologies, spatio-temporal databases
which store information on moving objects including vehicles
and mobile users have gained a lot of research interests. In this
paper, we propose an algorithm to extract mobility statistics
from indexed spatio-temporal datasets for the interactive
analysis of huge collections of moving object trajectories. We
focus on a mobility statistics value called the Markov transition
probability, which is based on a cell-based organization of a
target space and the Markov chain model. The proposed
algorithm efficiently computes the specified Markov transition probabilities with the help of a spatial index R-tree. We reduce
the statistics computation task to a kind of constraint
satisfaction problem that uses a spatial index, and utilize
internal representation of R-tree in an efficient manner.

Evaluation of a Mobility Statistics Extraction Scheme for Indexed Spatio-Temporal Datasets Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 2 ) page： 21-24 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

With the recent progress of spatial information technologies and mobile computing technologies, spatio-temporal databases which store information on moving objects including vehicles and mobile users have gained a lot of research interests. Here we focus on a mobility statistics value called the Markov transition probability, which is based on a cell-based organization of a target space and the Markov chain model. We have proposed an algorithm to extract mobility statistics from indexed spatio-temporal datasets for the interactive analysis of huge collections of moving object trajectories. The proposed algorithm efficiently computes the specified Markov transition probabilities with the help of a spatial index R-tree. In this paper, we evaluate the effectiveness of proposed method based on an experiment.

An Improved Approach to the Clustering Method Based on Forgetting Factors Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 3 ) page： 53-56 2003.12

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

Clustering plays important roles in various on-line
applications such as extraction of useful information from
news feeding services and selection of relevant documents
from incoming scientific articles in digital libraries. In
on-line environments, users generally have interests on
newer documents than older ones and have no interests
on obsolete old documents.
Based on this observation, we have proposed an on-line
document clustering method that incorporates the notion
of a forgetting factor to calculate document similarities.
The idea is that every document gradually losses its
weight (or memory) as time passes according to this factor.
Since our method generates clusters using a document
similarity measure based on the forgetting factor, newer
documents have much effect on the resulting cluster
structure than older ones. In this paper, we extend our
clustering method by using the K-means clustering
algorithm as its basis. The new algorithm has clear
semantics and supports incremental updates of cluster
structures.

Implementation and Evaluation of an Adaptive Neighborhood Information Retrieval System for Mobile Users Reviewed

Yoshiharu Ishikawa, Yuichi Tsukamoto, and Hiroyuki Kitagawa

Proceedings of the 3rd International Workshop on Web and Wireless Geographic Information Systems (W2GIS) page： 25-33 2003.12

Authorship：Lead author Language：English

Rapid development and ongoing research activities on
mobile devices, digital cartography, and global positioning
systems (GPSs) have brought us a new type of software
service―location-based services for moving objects (such
as people with mobile devices and vehicles with car navigation
systems). Realization of location-based services requires
new technologies to provide appropriate neighborhood
information to moving objects. A general approach
to providing neighborhood information to moving objects
is to retrieve objects in the neighborhood of a moving object
with a spatial query that uses the traditional Euclidean
distance. However, if we know the destination and the estimated
route of a moving object, we would be able to provide
more appropriate information to the object. Based on
this idea, we have developed adaptive spatial query generation
models that take the trajectory of a moving object into
consideration to retrieve desired information. In this paper,
we describe the design and implementation of the neighborhood
information retrieval system based on the models and
evaluate its effectiveness with experiments.

Requirement Specification and Derivation of ECA Rules for Integrating Multiple Dissemination-Based Information Sources Invited Reviewed

Tomoaki Kajino, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E87-D ( 1 ) page： 3-14 2004.1

Language：English Publishing type：Research paper (scientific journal)

The recent development of network technology has enabled us to access various information sources easily, and their integration has been studied intensively by the data engineering research community. Although technological advancement has made it possible to integrate existing heterogeneous information sources, we still have to deal with information sources of a new kind--dissemination-based information sources. They actively and autonomously deliver information from server sites to users. Integration of dissemination-based information sources is one of the popular research topics. We have been developing an information integration system in which we employ ECA rules to enable users to define new information delivery services integrating multiple existing dissemination-based information sources. However, it is not easy for users to directly specify ECA rules and to verify them. In this paper, we propose a scheme to specify new dissemination-based information delivery services using the framework of relational algebra. We discuss some important properties of the specification, and show how we can derive ECA rules to implement the services.

Development and Evaluation of a Spatial Database Retrieval System to Provide Neighborhood Information to Moving Objects Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J87-DI ( 2 ) page： 202-215 2004.2

Feature-based Distributed Object Search Using Signatures in Peer-to-Peer Environments Reviewed

Ryo Matsushita, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Proceedings of the 19th Annual ACM Symposium on Applied Computing (SAC 2004) page： 729-734 2004.3

Language：English

Peer-to-Peer (P2P) technology has attracted a lot of attention in recent years. Efficient object search is an important research issue in P2P environments, especially in those without centralized global indexes. Although a number of hash-based basic object search schemes are known to alleviate the problem, they cannot provide flexible feature-based object searches. This paper proposes a novel object search method using distributed frame sliced signatures, and looks at an appropriate choice of parameters to adapt the configuration to the object search and registration workload. It shows object search and registration schemes that take into account the number of messages and response times. Effectiveness of these schemes is evaluated through simulation experiments.

Exracting Mobility Statistics from Indexed Spatio-Temporal Databases Reviewed

Yoshiharu Ishikawa, Yuichi Tsukamoto, and Hiroyuki Kitagawa

Proceedings of the 2nd Workshop on Spatio-Temporal Database Management (STDBM'04) page： 9-16 2004.8

Authorship：Lead author Language：English

With the recent progress of spatial information
technologies and mobile computing technologies,
spatio-temporal databases that store information of
moving objects have gained a lot of research interests.
In this paper, we propose an algorithm
to extract mobility statistics from indexed spatiotemporal
datasets for interactive analysis of huge
collections of moving object trajectories. We focus
on mobility statistics called the Markov transition
probability, which is based on a cell-based organization
of a target space and the Markov chain model.
The algorithm computes the specified Markov transition
probabilities efficiently with the help of an Rtree
spatial index. It reduces the statistics computation
task to a kind of constraint satisfaction problem
and uses internal structure of an R-tree in an efficient
manner.

An Incremental Update Method for Materialized XSLT Views on RDBs Reviewed

Yoshiharu Ishikawa, Shusaku Miyasaka, and Hiroyuki Kitagawa

DBSJ Letters Vol. 3 ( 2 ) page： 25-28 2004.9

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

In information systems which provide XML documents,
RDBs are often used for data storage and XML
generation. XML documents in these systems can be
seen as database views. In this paper, we assume
an environment such that a client can define XML
views using XSLT over a remote relational database
and XML views are materialized on the client. We
propose an efficient method for updating materialized
XML views in an incremental manner. In our
approach, the view management system analyzes a
database schema and XSLT view definitions, and generates
update scripts. When a new update occurs, the
scripts are executed for XML view updates.

Web Link Analysis for Extracting SpatialInformation Hub Pages

Jianwei Zhang, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 3 ( 3 ) page： 9-12 2004.12

Language：Japanese Publishing type：Research paper (scientific journal)

Recently web mining that tries to find relevant information
from the vast amount of web pages has attracted
a lot of research interests. Besides, it is becoming
an important task to provide information related
to a user-specified geographic area. In this paper,
we propose a method to extract spatial information
hub pages. A spatial information hub is a webpage
which is related to a specified geographic area
and has much local information or many hyperlinks
to local web pages. We employ geographic information
to create spatial nodes and spatial links, and then conduct
link analysis based on the extended link structure.

Extended Link Analysis for Extracting Spatial Information Hubs

Jianwei Zhang, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

Proceedings of International Workshop on Challenges in Web Information Retrieval and Integration (WIRI 2005) page： 17-22 2005.4

Language：English

Recently, web mining that tries to find useful knowledge from the vast amount of web pages has attracted a lot of research interests. Besides, it is becoming an essential task to provide web pages related to a user-specified geographic area. In this paper, we propose an approach to extract spatial information hubs from the web. A spatial information hub is a web page which is related to a specified geographic area and has much local information and/or many hyperlinks to local web pages. In the traditional approach of web link analysis, the importance and quality of pages are judged only by their contents and hyperlink structures. However, we take their geographic localities into consideration. In our approach, we first extract geographic information from web pages to create spatial nodes and spatial links, then conduct a link analysis based on the extended link structures. We also show our approach works well based on the experiments.

LocalRank: Ranking Web Pages Considering Geographical Locality by Integrating Web and Databases Reviewed

Jianwei Zhang, Yoshiharu Ishikawa, Sayumi Kurokawa, and Hiroyuki Kitagawa

Proceedings of the 16th International Conference on Database and Expert Systems Applicatioins (DEXA 2005) page： 145-155 2005.8

Language：English

In this paper, we propose a method called LocalRank to rank web pages by integrating the web and a user database containing information on a specific geographical area. LocalRank is a rank value for a web page to assess its relevance degree to database entries considering geographical locality and its popularity on a local web space. In our method, we first construct a linked graph structure using entries contained in the database. The nodes of this graph consist of database entries and their related web pages. The edges in the graph are composed of semantic links including geographical links between these nodes, in addition to conventional hyperlinks. Then a link analysis is performed to compute a LocalRank value for each node. LocalRank can represent user's interest since this graph effectively integrates the web and the user database. Our experimental results for a local restaurant database shows that local web pages related to the database entries are highly ranked based on our method.

Novelty-based Incremental Document Clustering for On-line Documents Reviewed

Sophoin Khy, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

Proceedings of International Workshop on Challenges in Web Information Retrieval and Integration (WIRI 2006) page： 40 2006.4

Language：English

Document clustering has been used as a core technique in managing vast amount of data and providing needed information. In on-line environments, generally new information gains more interests than old one. Traditional clustering focuses on grouping similar documents into clusters by treating each document with equal weight. We proposed a novelty-based incremental clustering method for on-line documents that has biases on recent documents. In the clustering method, the notion of `novelty' is incorporated into a similarity function and a clustering method, a variant of the K-means method, is proposed. We examine the efficiency and behaviors of the method by experiments.

Dynamic Mobility Histogram Construction Based on Markov Chains Reviewed

Yoji Machida, Yoshiharu Ishikawa, Hiroyuki Kitagawa

Vol. 5 ( 1 ) page： 89-92 2006.6

Language：Japanese Publishing type：Research paper (scientific journal)

For the accumulation and analysis of a large collection
of moving object trajectories, our group focuses
on the research on a mobility histogram to summarize
moving object trajectories. The histogram is based on
a mobility statistics model called the Markov chain
model. We provide a mobility histogram datacubelike
logical representation and support an OLAP-style
analysis. As its physical structure, we introduce a tree
structure that efficiently works in a limited memory
space. We describe the details of the method and evaluate
its performance based on experiments.

Incremental Clustering Based on Novelty of On-line Documents Reviewed

Sophoin Khy, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 5 ( 1 ) page： 57-60 2006.6

Language：English Publishing type：Research paper (scientific journal)

Clustering has been widely used as a fundamental
method in many areas such as characterization
and classification. Various clustering researches have
been conducted since decades ago. In previous papers,
we presented a novelty-based incremental document
clustering method which considers novelty of
on-line documents in its similarity measure and performs
clustering based on an extended algorithm of
the K-means method. This paper further examines the
performance of the incremental and non-incremental
processing of the clustering method and effect of parameter
values on the method by showing the experimental
results.

A Dynamic Mobility Histogram Construction Method Based on Markov Chains Reviewed

Yoshiharu Ishikawa, Yoji Machida, and Hiroyuki Kitagawa

Proceedings of the 18th International Conference on Scientific and Statistical Database Management (SSDBM 2006) page： 359-368 2006.7

Authorship：Lead author Language：English

With the recent progress of spatial information technologies and communication technologies, it has become easier to track positions of a large number of moving objects in real-time. Mobility statistics plays an important role in the interactive analysis of a large collection of moving objects trajectories and its use of movement pattern prediction. The development of an effective mobility statistics measure and its efficient computation method are critical issues. Thus, we propose an approach for constructing a mobility histogram to summarize a number of moving object trajectories. The histogram is based on a mobility statistics model called the Markov chain model. To facilitate an interactive analysis performed by a user, we provide a mobility histogram data cube-like logical representation and support an OLAP-style analysis. Since trajectory data is often received continuously as a trajectory stream, we have to support dynamic histogram construction and maintenance. We introduce a tree structure as the physical representation of a histogram and present histogram construction and maintenance methods that work efficiently within the given upperbound size. We evaluate the performance and the precision of the proposed method by means of experiments.

A Dynamic Mobility Histogram Construction Method Based on Markov Chains Reviewed

Yoshiharu Ishikawa, Yoji Machida, Hiroyuki Kitagawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J90-D ( 2 ) page： 311-324 2007.2

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

Due to the progress of GPS and communication technologies, it has become easier to track positions of moving objects. By monitoring and aggregating the movements of a large number of objects in real-time, we can analyze and estimate their behaviors effectively. For this purpose, we propose an approach to constructing a mobility histogram for the summarization of a large volume of moving object trajectories. The histogram is based on a mobility statistics model called the Markov chain model. We provide a mobility histogram data cube-like logical representation and support an OLAP-style analysis. We introduce a tree structure as its physical representation and present approximated histogram construction methods for the reduction of the storage size. Since trajectory data is often received continuously as a trajectory stream, we enable efficient histogram construction for the real-time processing. We evaluate the performance and the precision of the proposed methods based on the experiments.

T-Scroll: A Visualization System for Temporally Changing Topics Reviewed

Mikine Hasegawa, Yoshiharu Ishikawa

DBSJ Letters Vol. 6 ( 1 ) page： 149-152 2007.6

Language：Japanese Publishing type：Research paper (scientific journal)

On the Internet, delivery of a large amount of documents such as news articles is continually performed everyday. In this paper, we describe an information visualization system T-Scroll to show the transition of topics contaned in such documents to the user and to provide an overview of their trends. The system is built on a clustering system for time-sereis of documents and presents relationships between clusters like a scroll. This paper describes the idea, the functions, and the implementation of the system.

Record Extraction Based on User Feedback and Document Selection Reviewed

Jianwei Zhang, Yoshiharu Ishikawa, Hiroyuki Kitagawa

Proceedings of the Joint Conference of the 9th Asia-Pacific Web Conference and the 8th International Conference on Web-Age Information Management (APWeb/WAIM07) page： 574-585 2007.6

Language：English

In recent years, the research of record extraction from large document data is becoming popular. However there still exist some problems in record extraction. 1) when large document data is used for the target of information extraction, the process usually becomes very expensive. 2) it is also likely that extracted records may not pertain to the user's interest on the aspect of the topic. To address these problems, in this paper we propose a method to efficiently extract those records whose topics agree with the user's interest. To improve the efficiency of the information extraction system, our method identifies documents from which useful records are probably extracted. We make use of user feedback on extraction results to find topic-related documents and records. Our experiments show that our system achieves high extraction accuracy across different extraction targets.

T-Scroll: Visualizing Trend in a Time-series of Documents for Interactive User Exploration Reviewed

Yoshiharu Ishikawa, Mikine Hasegawa

Proceedings of 11th European Conference on Research and Advanced Technology for Digital Libraries (ECDL 2007) page： 235-246 2007.9

Authorship：Lead author Language：English

On the Internet, a large number of documents such as news articles and online journals are delivered everyday. We often have to review major topics and topic transitions from a large time-series of documents, but it requires much time and effort to browse and analyze the target documents. We have therefore developed an information visualization system called T-Scroll (Trend/Topic-Scroll) to visualize the transition of topics extracted from those documents. The system takes periodical outputs of the underlying clustering system for a time-series of documents then visualizes the relationships between clusters as a scroll. Using its interaction facility, users can grasp the topic transitions and the details of topics for the target time period. This paper describes the idea, the functions, the implementation, and the evaluation of the T-Scroll system.

Record Extraction from Large-scale Text Resources Considering Topics Reviewed

Jianwei Zhang, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

IPSJ Transactions on Databases Vol. 48 ( SIG 14(TOD 35) ) page： 107-123 2007.9

Language：Japanese Publishing type：Research paper (scientific journal)

In recent years, the research on record extraction from a large number of text documents is becoming popular. However, there still exist some problems in record extraction. 1) When a large number of documents are used for the target of information extraction, the process usually becomes very time-consuming. 2) It is also likely that extracted records may not pertain to the user's interest on the aspect of the topic. To address these problems, in this paper we propose a method for efficiently extracting those records whose topics are relevant to the user's interest. To improve the efficiency of the information extraction system, our method identifies documents from which useful records are probably extracted. Those selected documents are first processed in order to reduce processing cost. Moreover, from these documents user-desired records are apt to be extracted so that high extraction accuracy is obtained. Our experiments show that our system reduces the processing cost with achieving high extraction accuracy.

Processing Spatial Queries Based on Imprecise Location Information Reviewed

Yoshiharu Ishikawa

DBSJ Letters Vol. 6 ( 2 ) page： 49-52 2007.9

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

In sensor environments and mobile robot applications, we often find the situation in which the location of an object is imprecise due to measurement errors and/or object movements. In this paper, we present an approach for processing spatial queries when the location of a query object is specified by a probabilistic density function based on the Gaussian distribution.

T-Scroll: A Trend Visualization System Based on Clustering of a Time-series of Documents Reviewed

Mikine Hasegawa, Yoshiharu Ishikawa

IPSJ Transactions on Databases Vol. SIG 20 ( TOD 36 ) page： 61-78 2007.12

Language：Japanese Publishing type：Research paper (scientific journal)

On the Internet, a large number of documents such as news articles and online journals are delivered everyday. Documents continually delivered with timestamps such as issue dates are called a time-series of documents. We often need to review major topics and trends from a large time-series of documents, but it requires much time and effort to browse and analyze the target documents. We have therefore developed an information visualization system called T-Scroll (Trend/Topic-Scroll) to display the overall trends extracted from those documents. The system takes periodical outputs of the underlying clustering system for a time-series of documents then visualizes the relationships between clusters as a scroll. Using its interaction facility, users can grasp the trends and the details of the topics contained in the documents. This paper describes the idea, the functions, the implementation, and the evaluation of the T-Scroll system.

A Novelty-based Clustering Method for On-line Documents Reviewed

Sophoin Khy, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

World Wide Web Journal Vol. 11 ( 1 ) page： 1-37 2008.3

Language：English Publishing type：Research paper (scientific journal)

In this paper, we describe a document clustering method called novelty-based document clustering. This method clusters documents based on similarity and novelty. The method assigns higher weights to recent documents than old ones and generates clusters with the focus on recent topics. The similarity function is derived probabilistically, extending the conventional cosine measure of the vector space model by incorporating a document forgetting model to produce novelty-based clusters. The clustering procedure is a variation of the K-means method. An additional feature of our clustering method is an incremental update facility, which is applied when new documents are incorporated into a document repository. Performance of the clustering method is examined through experiments. Experimental results show the efficiency and effectiveness of our method.

Traceable P2P Record Exchange Based on Database Technologies Reviewed

Fengrong Li and Yoshiharu Ishikawa

Proceedings of the 10th Asia Pacific Web Conference (APWeb 2008) page： 475-486 2008.4

Language：English

Information exchanges in P2P networks have become very popular in recent years. However, tracing how data circulates between peers and how data modifications are performed during the circulation before reaching the destination are not easy because data replications and modifications are performed independently by peers. This creates a lack of reliability among the records exchanged. To provide reliable and flexible information exchange facilities in P2P networks, we propose a framework for a record exchange system based on database technologies. The system consists of three layers: a user layer, a logical layer and a physical layer. Its tracing operations are executed as distributed recursive queries among cooperating peers in a P2P network. This paper describes the concept and overviews the framework.

Monitoring Aggregate k-NN Objects in Road Networks Reviewed

Lu Qin, Jeffrey Xu Yu, Bolin Ding, and Yoshiharu Ishikawa

Proceedings of 20th International Conference on Scientific and Statistical Database Management (SSDBM 2008) page： 168-186 2008.7

Language：English Publishing type：Research paper (scientific journal)

In recent years, there is an increasing need to monitor k nearest neighbor (k-NN) in a road network. There are existing solutions on either monitoring k-NN objects from a single query point over a road network, or computing the snapshot k-NN objects over a road network to minimize an aggregate distance function with respect to multiple query points. In this paper, we study a new problem that is to monitor k-NN objects over a road network from multiple query points to minimize an aggregate distance function with respect to the multiple query points. We call it a continuous aggregate k-NN (CANN) query. We propose a new approach that can significantly reduce the cost of computing network distances when monitoring aggregate k-NN objects on road networks. We conducted extensive experimental studies and confirmed the fficiency of our algorithms.

Traceable P2P Record Exchange: A Database-Oriented Approach Reviewed

Fengrong Li, Takuya Iida, and Yoshiharu Ishikawa

Frontiers of Computer Science in China Vol. 2 ( 3 ) page： 257-267 2008.9

Language：English Publishing type：Research paper (scientific journal)

In recent years, peer-to-peer (P2P) technologies are used for flexible and scalable information exchange in the Internet, but there exist problems to be solved for reliable information exchange. It is important to trace how data circulates between peers and how data modifications are performed during the circulation before reaching the destination for enhancing the reliability of exchanged information. However, such lineage tracing is not easy in current P2P networks, since data replications and modifications are performed independently by autonomous peers---this creates a lack of reliability among the records exchanged. In this paper, we propose a framework for traceable record exchange in a P2P network. By managing historical information in distributed peers, we make the modification and exchange histories of records traceable. One of the features of our work is that the database technologies are utilized for realizing the framework. Histories are maintained in a relational database in each peer, and tracing queries are written in the datalog query language and executed in a P2P network by cooperating peers. This paper describes the concept of the framework and overviews the approach to query processing.

A Query Language and Its Processing for Time-Series Document Clusters Reviewed

Sophoin Khy, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

Proceedings of the 11th International Conference on Asia-Pacific Digital Libraries (ICADL 2008) page： 82-92 2008.12

Language：English

Document clustering methods for time-series documents produce a sequence of snapshots of clustering over time. Analyzing the contents (topics) and trends in a long sequence of clustering snapshots is hard and requires efforts since there are too many number of clusters; a user may need to access every cluster or read every document contained in each cluster. In this paper, we propose a framework to find clusters of user interest and change patterns called transition patterns involving the clusters. A cluster in a clustering result may persist in another cluster, branch into more than one cluster, merge with other clusters to form one cluster, or disappear in the adjacent clustering result. This research aims at providing users facilities to retrieve specific transition patterns in the clustering results. For this purpose, we propose a query language for time-series document clustering results and an approach to query processing. The first experimental results on TDT2 corpus clustering results are presented.

Range Query Processing for Imprecise Objects with Gaussian Distributions

Yoshiharu Ishikawa

The 4th Korea-Japan Workshop (KJDB 2008) page：（招待講演） 2008.9

Querying Topic Evolution in Time Series Document Clusters Reviewed

Sophoin Khy, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

Vol. 7 ( 3 ) page： 7-12 2008.12

Language：English Publishing type：Research paper (scientific journal)

A document clusteringmethod for time series documents produces a sequence of clustering results over time. Analyzing the contents and trends in a long sequence of clustering results is a hard and tedious task since there are too many number of clusters. In this paper, we propose a framework to find clusters of users' topics of interest and evolution patterns called transition patterns involving
the topics. A cluster in a clustering result may continue to appear in or move to another cluster, branch into more than one cluster, merge with other clusters to form one cluster, or disappear in the adjacent clustering result. This research aims at providing users facilities to retrieve specific transition patterns in the clustering results. For this purpose, we propose a query language for time series document clustering results and an approach to query processing. The first experimental results on TDT2 corpus clustering results are presented.

Spatial Range Querying for Gaussian-Based Imprecise Query Objects Reviewed

Yoshiharu Ishikawa, Yuichi Iijima, and Jeffrey Xu Yu

Proceedings of the 25th International Conference on Data Engineering (ICDE 2009) page： 676-687 2009.4

Authorship：Lead author Language：English

In sensor environments and moving robot applications, the position of an object is often known imprecisely because of measurement error and/or movement of the object. In this paper, we present query processing methods for spatial databases in which the position of the query object is imprecisely specified by a probability density function based on a Gaussian distribution. We define the notion of a {\em probabilistic range query\/} by extending the traditional notion of a spatial range query, then present three strategies for query processing. Since the qualification probability evaluation of target objects requires numerical integration by a method such as the Monte Carlo method, reduction of the number of candidate objects that should be evaluated has a large impact on query performance. We compare three strategies and their combinations in terms of the experiments and evaluate their effectiveness.

`Pay-as-you-go' Processing for Tracing Queries in a P2P Record Exchange System Reviewed

Fengrong Li, Takuya Iida, and Yoshiharu Ishikawa

Proceedings of the 14th International Conference on Database Systems for Advanced Applications (DASFAA 2009) page： 323-327 2009.4

Language：English

In recent years, data provenance or lineage tracing has become an acute issue in the database research. Our target is the data provenance issue in peer-to-peer (P2P) networks where duplicates and modifications of data occur independently in autonomous peers. To ensure reliability among the exchanged data in P2P networks, we have proposed a reliable record exchange framework with tracing facilities based on database technologies in [5,6]. The framework is based on the "pay-as-you-go" approach in which the system maintains the minimum amount of information for tracing with low maintenance cost and a user pays the cost when he or she issues a tracing query to the system. This paper focuses on its two alternative query processing strategies and compare their characteristics according to the performance.

Finding Probabilistic Nearest Neighbors for Query Objects with Imprecise Locations Reviewed

Yuichi Iijima and Yoshiharu Ishikawa

Proceedings of the 10th International Conference on Mobile Data Management (MDM 2009) page： 52-61 2009.5

Language：English

A nearest neighbor query is an important notion in spatial databases and moving object databases. In the emerging application fields of moving object technologies, such as mobile sensors and mobile robotics, the location of an object is often imprecise due to noise and estimation errors. We propose techniques for processing a nearest neighbor query when the location of the query object is specified by an imprecise Gaussian distribution. First, we consider two query processing strategies for pruning candidate objects, which can reduce the number of objects that require numerical integration for computing the qualification probabilities. In addition, we consider a hybrid approach that combines the two strategies. The performance of the proposed methods is evaluated using test data.

Event-driven Queries for a Traceable P2P Record Exchange System Reviewed

Takuya Iida, Fengrong Li, Yoshiharu Ishikawa

DBSJ Journal Vol. 8 ( 1 ) page： 95-100 2009.6

Language：Japanese Publishing type：Research paper (scientific journal)

To assure the reliability of exchanged data in peer-to-peer (P2P) networks, we are developing PIREX system, a P2P record exchange system that supports trace facilities. In this paper, we present the feature of its event-driven queries. Using event-driven queries, we can monitor updates and exchanges of information without heavy network load. We discuss the outline of the feature and implementation ideas.

Effective Top-k Keyword Search in Relational Databases Considering Query Semantics Reviewed

Yanwei Xu, Yoshiharu Ishikawa, and Jihong Guan

Proceedings of International Workshop on DataBase and Information Retrieval and Aspects in Evaluating Holistic Quality of Ontology-Based Information Retrieval (DBIR-ENQOIR 2009) (APWeb-WAIM 2009 Workshop) page： 172-184 2009.9

Language：English

Keyword search in relational databases has recently emerged
as a new research topic. As a search result is often assembled from multiple relational tables, existing IR-style ranking strategies can not be applied directly. In this paper, we propose a novel IR ranking strategy considering query semantics for eective keyword search. The experimental results on a large-scale real database emonstrate that our method results in signicant improvement in terms of retrieval eectiveness as compared to previous ranking strategies.

Skyline Queries Based on User Locations and Preferences for Making Location-Based Recommendations Reviewed

Kazuki Kodama, Yuichi Iijima, Xi Guo, Yoshiharu Ishikawa

Proceedings of 2009 International Workshop on Location Based Social Networks (LBSN 2009) page： 6-13 2009.11

Language：English

Due to the recent development of mobile computing and communication network technologies, information services for mobile phone users and car navigation systems have becomeof
some importance. Since these mobile devices have limited display sizes, we often need to select carefully the appropriate information to be presented to the user. However,
it is not easy to select the "appropriate" information because users have different contexts and preferences.
In this paper, we present an approach to recommending items such as restaurants to a mobile user taking into account his current location and preferences. In our framework,
a user initially provides a profile, which records preferences as relative orders within predefined categories such as food types and prices. We then select items to be recommended
from the database based on the user's profile as well as the current location. To select good items, we extend the notion of spatial skyline queries to incorporate not
only distance information but also categorical preference information.
Based on the proposed approach, a prototype system has been implemented in a small mobile PC containing a small embedded RDBMS. The facilities of the RDBMS, such as
spatial indexes, were used to process our skyline queries effectively.

データベース（特集：ロボットを進化させる最先端IT技術）

石川佳治，喜連川優

日本ロボット学会誌 Vol. 28 ( 3 ) page： 36-39 2010.3

Efficient Continuous Top-k Keyword Search in Relational Databases Reviewed

Yanwei Xu, Yoshiharu Ishikawa, and Jihong Guan

Proceedings of 11th International Conference on Web-Age Information Management (WAIM 2010) page： 755-767 2010.4

Language：English

Keyword search in relational databases has been widely studied in recent years. Most of the previous studies focus on how to answer an instant keyword query. In this paper, we focus on how to find the top-k answers in relational databases for continuous keyword queries efficiently. As answering a keyword query involves a large number of join operations between relations, reevaluating the keyword query when the database is updated is rather expensive. We propose a method to compute a range for the future relevance score of query answers. For each keyword query, our method computes a state of the query evaluation process, which only contains a small amount of data and can be used to maintain top-k answers when the database is continually growing. The experimental results show that our method can be used to solve the problem of responding to continuous keyword searches for a relational database that is updated frequently.

Query Processing with Materialized Views in a Traceable P2P Record Exchange Framework Reviewed

Fengrong Li and Yoshiharu Ishikawa

Proceedings of WAIM 2010 International Workshops page： 246-257 2010.4

Language：English

Materialized views which are derived from base relations and stored in the database are often used to speed up query processing. In this paper, we leverage them in a traceable peer-to-peer (P2P) record exchange framework which was proposed to ensure reliability among the exchanged data in P2P networks where duplicates and modifications of data occur independently in autonomous peers. In our proposed framework, the provenance/lineage of the exchanged data can be available by issuing tracing queries. Processing for tracing queries was based on the "pay-as-you-go" approach. The framework can achieve low maintenance cost since each peer only maintains minimum amount of information for tracing. However, the user must pay relatively high query processing cost when he or she issues a query. We consider that the use of materialized views allows more efficient query execution plans. In this paper, we focus on how to incorporate query processing based on materialized views in our framework.

Query Processing in a Traceable P2P Record Exchange Framework Reviewed

Fengrong Li and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E93-D ( 6 ) page： 1433-1446 2010.6

Processing Methods for Nearest Neighbor Queries Based on Imprecise Location Information Reviewed

Yuichi Iijima and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J93-D ( 6 ) page： 781-794 2010.6

Language：Japanese Publishing type：Research paper (scientific journal)

A nearest neighbor query is an important notion in location-based applications such as mobile robotics and mobile sensor networks. In these application fields, query processing methods considering impreciseness are required because obtained location information of the query object is usually imprecise due to such as control noise and measurement errors. In this paper, we propose techniques for processing a nearest neighbor query when the location of the query object is specified by an imprecise Gaussian distribution. Moreover, we compare the performance of the proposed methods by experiments.

Direction-Based Spatial Skylines Reviewed

Xi Guo, Yoshiharu Ishikawa, and Yunjun Gao

Proceedings of Ninth International ACM Workshop on Data Engineering for Wireless and Mobile Access (MobiDE 2010) page： 73-80 2010.6

Language：English

Traditional location-based services recommend nearest objects to the user by considering their spatial proximity. However, an object not only has its distance but also has its direction which originates from the user to it. In this paper, we study direction-based spatial skyline queries (DSS queries) which retrieve nearest objects around the user from different directions. The closer object is better than or dominates the further object if they are in the same direction. The objects that cannot be dominated by any other object are included in the direction-based spatial skyline (DSS). We propose algorithms to answer snapshot queries which find objects on the DSS according to the user's current position. We also develop algorithms to support continuous queries which retrieve objects on the DSS while the user is moving linearly. Extensive experiments verify the performance of our proposed algorithms using both real and synthetic datasets.

Query Processing with Materialized Views in a Traceable P2P Record Exchange Framework Reviewed

Fengrong Li and Yoshiharu Ishikawa

Proceedings of WAIM 2010 International Workshops page： 246-257 2010.7

Language：English

DOI： 10.1007/978-3-642-16720-1_25

Efficient Continuous Top-k Keyword Search in Relational Databases Reviewed

Yanwei Xu, Yoshiharu Ishikawa, Jihong Guan

Proceedings of 11th International Conference on Web-Age Information Management (WAIM 2010) page： 755-767 2010.7

Language：English

DOI： 10.1007/978-3-642-14246-8_71

Anonymizing User Location and Profile Information for Privacy-aware Mobile Services Reviewed

Masanori Mano and Yoshiharu Ishikawa

Proceedings of 2nd ACM SIGSPATIAL International Workshop on Location Based Social Networks (LBSN 2010) page： 68-75 2010.11

Language：English

Due to the growing use of mobile devices, location-based services have become popular. A location service often requires the user's exact location to provide appropriate services and this brings the risk of threats to privacy. In this paper, we propose an anonymization method for users of location-based services in mobile environments.

The anonymization approach is based on the well-known k-anonymity concept, but has additional features. We consider the situation that a mobile service (e.g., mobile advertisement) utilizes mobile users' profiles for its service. Since a profile contains privacy information such as the age and address of the user, the use of profile information brings another kind of privacy threat.

The anonymization method proposed in this paper considers not only location information but also privacy-related attributes in the user's profile. The location anonymizer, a trusted third-party placed between users and mobile application services, anonymizes the location and profile attributes based on the request. We define a similarity measure between mobile users for anonymization purposes. The similarity is used for related users in terms of their locations and profile attributes. We present the concept behind our method and the anonymization algorithm, and then show some experimental results.

Using Materialized Views to Enhance a Traceable P2P Record Exchange Framework Reviewed

Fengrong Li, Yoshiharu Ishikawa

Journal of Advances in Information Technology Vol. 2 ( 1 ) page： 27-39 2011.2

Language：English Publishing type：Research paper (scientific journal)

P2P technologies are drawing increasing attention nowadays, and have been widely deployed on the Internet for various purposes. Unlike the traditional client-server architecture, a P2P network allows all computers to communicate and share resources as equals and does not depend on a central server for control. In such an environment, tracing how data is copied between peers and how data modifications are performed are not easy because data replications and modifications are performed independently by autonomous peers. This creates inconsistencies in exchanged information and results in a lack of trustworthiness. To provide reliable and flexible information exchange facility in P2P networks, we have proposed a framework for enabling traceable record exchange. In this framework, a computer can exchange structured records with a predefined schema with other peers. The framework supports a tracing facility to query the lineage of the records obtained. A tracing query is described in Datalog and executed as a recursive query among cooperating peers in a P2P network. In the query execution process, the exchange and modification histories of the queried records are collected dynamically from relevant peers.
In this paper, we focus on how to enhance the traceable P2P record exchange framework using materialized views. First, we discuss how to construct materialized views in our framework. Then we present methods for reducing query processing cost and providing fault tolerance using the materialized views.

A Stream Algorithm for Subsequence Matching Reviewed

Machiko Toyoda, Yasushi Sakurai, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. J94-D ( 7 ) page： 1058-1070 2011.7

Language：Japanese Publishing type：Research paper (scientific journal)

We define and solve the problem of 'cross-similarity' in data streams. Given multiple data streams, our goal is to find partial similarity between them. To achieve the above goal, we exploit the well-known Dynamic Time Warping (DTW) distance. We present a one-pass algorithm. Our algorithm is strictly based on DTW and continuously works in a streaming fashion. Instead of straightforwardly using DTW, our algorithm achieves a great resource reduction in terms of time and space. We provide a theoretical analysis and prove that our algorithm does not sacrifice accuracy. Our experimental evaluation shows that CrossMatch can incrementally capture cross-similarity, efficiently and effectively.

Multi-Objective Optimal Combination Queries Reviewed

Xi Guo and Yoshiharu Ishikawa

Proceedings of 22nd International Conference on Database and Expert Systems (DEXA 2011), Part I page： 47-61 2011.8

Language：English

Multi-objective optimization problem finds out optimal objects w.r.t. several objectives rather than a single objective. We propose a new problem called a multi-objective optimal combination problem (MOC problem) which finds out object combinations w.r.t. multiple objectives. A combination dominates another combination if it is not worse than anther one in all attributes and better than another one in one attribute at least. The combinations, which cannot be dominated by any other combinations, are optimal. We propose an efficient algorithm to find out optimal combinations by reducing the search space with a lower bound reduction method and an upper bound reduction method based on the R-tree index. We implemented the proposed algorithm and conducted experiments on synthetic data sets.

DOI： 10.1007/978-3-642-23088-2_4

An Index Structure for Spatial Range Querying on Gaussian Distributions Reviewed

Kazuki Kodama, Tingting Dong, Yoshiharu Ishikawa

Proceedings of the Fifth International Workshop on Management of Uncertain Data (MUD 2011) page： 1-7 2011.8

Language：English

In the research area of spatial databases, query processing based on uncertain location information has become an important research topic. In this paper, we propose an index structure for the case that the locations of a query object and target objects are imprecise and specified by Gaussian distributions with different parameters. The index structure efficiently supports probabilistic spatial range queries, which is an enhanced version of traditional spatial range queries, by considering the properties of Gaussian distributions. We implement the proposed index structure using GiST, a generalized index structure, and we evaluate its performance based on the experiments.

Simulation Based Analysis for a Traceable P2P Record Exchange Framework Reviewed

Fengrong Li, Yoshiharu Ishikawa

Proceedings of 4th International Conference on Data Management in Grid and P2P Systems (Globe 2011) page： 49-60 2011.9

Language：English

P2P technologies are getting more and more attention lately. However, unlike the traditional client-server architecture, a P2P network allows all computers to communicate and share resources as equals without central server control. This causes inconsistency in exchanged information and results in lack of trustworthiness. To provide trustful and flexible information exchange facility in P2P networks, we proposed a traceable P2P record exchange framework. In this framework, a peer can exchange structured records with a predefined schema among other peers. The framework supports a tracing facility to query the lineage of the obtained records based on database technologies. A tracing query is described in Datalog and executed as a recursive query among cooperating peers in a P2P network. In this paper, we focus on analyzing and verifying the traceable P2P record exchange framework based on simulation experiments in three different example P2P networks.

DOI： 10.1007/978-3-642-22947-3_5

Direction-Based Surrounder Queries for Mobile Recommendations Reviewed

Xi Guo, Baihua Zheng, Yoshiharu Ishikawa, Yunjun Gao

The VLDB Journal Vol. 20 ( 5 ) page： 743-766 2011.10

Language：English Publishing type：Research paper (scientific journal)

Location-based recommendation services recommend objects to the user based on the user's preferences. In general, the nearest objects are good choices considering their spatial proximity to the user. However, not only the distance of an object to the user but also their directional relationship are important. Motivated by these, we propose a new spatial query, namely a direction-based surrounder (DBS) query, which retrieves the nearest objects around the user from different directions. We define the DBS query not only in a two-dimensional Euclidean space E but also in a road network R. In the Euclidean space E, we consider two objects a and b are directional close w.r.t. a query point q iff the included angle aqb is bounded by a threshold specified by the user at the query time. In a road network R, we consider two objects a and b are directional close iff their shortest paths to q overlap. We say object a dominates object b iff they are directional close and meanwhile a is closer to q than b. All the objects that are not dominated by others based on the above dominance relationship constitute direction-based surrounders (DBSs). In this paper, we formalize the DBS query, study it in both the snapshot and continuous settings, and conduct extensive experiments with both real and synthetic datasets to evaluate our proposed algorithms. The experimental results demonstrate that the proposed algorithms can answer DBS queries efficiently.

DOI： 10.1007/s00778-011-0241-y

Efficient Continual Top-k Keyword Search in Relational Databases Reviewed

Yanwei Xu, Yoshiharu Ishikawa, and Jihong Guan

Journal of Information Processing (IPSJ) Vol. 20 ( 1 ) page： 114-127 2012.1

Language：English Publishing type：Research paper (scientific journal)

Keyword search in relational databases has been widely studied in recent years because it requires users neither to master a certain structured query language nor to know the complex underlying database schemas. Most existing methods focus on answering snapshot keyword queries in static databases. In practice, however, databases are updated frequently, and users may have long-term interests on specific topics. To deal with such situations, it is necessary to build effective and efficient facilities in a database system to support continual keyword queries. In this paper, we propose an efficient method for answering continual keyword queries over relational databases. The proposed method consists of two core algorithms. The first one computes a set of potential top-k results by evaluating the range of the future relevance score for every query result and creates a light-weight state for each keyword query. The second one uses these states to maintain the top-k results of keyword queries while the database is continually being updated. Experimental results validate the effectiveness and efficiency of the proposed method.

DOI： 10.2197/ipsjjip.20.114

Scalable Top-k Keyword Search in Relational Databases Reviewed

Yanwei Xu, Jihong Guan, Yoshiharu Ishikawa

Proceedings of 17th International Conference on Database Systems for Advanced Applications (DASFAA 2012) Vol. 2 page： 65-80 2012.4

Language：English

Keyword search in relational databases has been widely studied in recent years because it does not require users neither to master a certain structured query language nor to know the complex underlying database schemas. There would be a huge number of valid results for a keyword query in a large database. However, only the top 10 or 20 most relevant matches for the keyword query - according to some definition of 'Relevance' - are generally of interest. In this paper, we propose an efficient method for answering top-k keyword queries over relational databases. The proposed method is built on an existing scheme of keyword search on relational data streams, but incorporates the ranking mechanisms into the query processing methods and makes two improvements to support top-k keyword search in relational databases. Experimental results validate the effectiveness and efficiency of the proposed method.

DOI： 10.1007/978-3-642-29035-0_5

Hadoop環境における空間分割による並列全k近傍問合せ処理 Reviewed

横山拓也, 石川佳治, 鈴木優

日本データベース学会論文誌 Vol. 11 ( 1 ) page： 25-30 2012.6

Language：Japanese Publishing type：Research paper (scientific journal)

指定された点に対して最も近い$k$個の点を求める$k$最近傍問合せは，空間データベースでは基本的な問合せの1つである．これに関連して，データ集合中の各点について，それぞれの$k$最近傍を一度に求める問合せを全$k$最近傍問合せという．本研究では，この全k最近傍問合せをMapReduceフレームワーク上で行う手法を提案する．空間をセルに分割し，全$k$最近傍問合せの処理をMapReduceの並列分散処理方式に合った形で実行する．分割により生じる問題にMapReduceフレームワークに適した形で対応するための，対象データの分布情報を考慮した改善策についても提案を行う．

Processing All k-Nearest Neighbor Queries in Hadoop Reviewed

Takuya Yokoyama, Yoshiharu Ishikawa, Yu Suzuki

Proceedings of the 13th International Conference on Web-Age Information Management (WAIM 2012) page： 346-351 2012.8

Language：English

A k-nearest neighbor (k-NN) query, which retrieves nearest k points from a database is one of the fundamental query types in spatial databases. An all k-nearest neighbor query (AkNN query), a variation of a k-NN query, determines the k-nearest neighbors for each point in the dataset in a query process. In this paper, we propose a method for processing AkNN queries in Hadoop. We decompose the given space into cells and execute a query using the MapReduce framework in a distributed and parallel manner. Using the distribution statistics of the target data points, our method can process given queries efficiently.

DOI： 10.1007/978-3-642-32281-5_34

Privacy Preservation for Location-Based Services Based on Attribute Visibility Reviewed

Masanori Mano, Xi Guo, Tingting Dong, Yoshiharu Ishikawa

Proceedings of the International Workshop on Information Management in Mobile Applications (IMMoA 2012) page： 33-41 2012.8

Language：English

To provide a high-quality mobile service in a safe way, many techniques for \emph{location anonymity} have been proposed in recent years.
Advanced location-based services such as mobile advertisement services may use not only users' locations but also users' attributes.
However, the existing location anonymization methods do not consider attribute information and may result in low-quality privacy protection.
In this paper, we propose the notion of \emph{visibility}, which describes the degree that an adversary can infer the identity of the user by an observation. Then we present an anonymization method which considers not only location information but also users' attributes. We show several strategies for the anonymization process and evaluate them based on the experiments.

Combination Skyline Queries Reviewed

Xi Guo, Chuan Xiao, Yoshiharu Ishikawa

Transactions on Large-Scale Data- and Knwoledge-Centered Systems Vol. 6 page： 1-30 2012.9

Language：English Publishing type：Research paper (scientific journal)

Given a collection of data objects, the skyline problem is to select the objects which are not dominated by any others. In this paper, we propose a new variation of the skyline problem, called the combination skyline problem. The goal is to find the fixed-size combinations of objects which are skyline among all possible combinations. Our problem is technically challenging as traditional skyline approaches are inapplicable to handle a huge number of possible combinations. By indexing objects with an R-tree, our solution is based on object-selecting patterns that indicate the number of objects to be selected for each MBR. We develop two major pruning conditions to avoid unnecessary expansions and enumerations, as well as a technique to reduce space consumption on storing the skyline for each rule in the object-selecting pattern. The efficiency of the proposed algorithm is demonstrated by extensive experiments on both real and synthetic datasets.

DOI： 10.1007/978-3-642-34179-3_1

Efficient Error-tolerant Query Autocompletion Reviewed

Chuan Xiao, Jianbin Qin, Wei Wang, Yoshiharu Ishikawa, Koji Tsuda, Kunihiko Sadakane

Proceedings of the VLDB Endowment (PVLDB) Vol. 6 ( 6 ) page： 373-384 2013.4

Language：English Publishing type：Research paper (scientific journal)

Query autocompletion is an important feature saving users many keystrokes from typing the entire query. In this paper we study the problem of query autocompletion that tolerates errors in users' input using edit distance constraints. Previous approaches index data strings in a trie, and continuously maintain all the prefixes of data strings whose edit distance from the query are within the threshold. The major inherent problem is that the number of such prefixes is huge for the first few characters of the query and is exponential in the alphabet size. This results in slow query response even if the entire query approximately matches only few prefixes.
In this paper, we propose a novel neighborhood generation-based algorithm, IncNGTrie, which can achieve up to two orders of magnitude speedup over existing methods for the error-tolerant query autocompletion problem. Our proposed algorithm only maintains a small set of active nodes, thus saving both space and time to process the query. We also study efficient duplicate removal which is a core problem in fetching query answers. In addition, we propose optimization techniques to reduce our index size, as well as discus- sions on several extensions to our method. The efficiency of our method is demonstrated against existing methods through extensive experiments on real datasets.

Pattern Discovery in Data Streams under the Time Warping Distance Reviewed

Machiko Toyoda, Yasushi Sakurai, Yoshiharu Ishikawa

The VLDB Journal Vol. 6 ( 6 ) page： 295-318 2013.6

Language：English Publishing type：Research paper (scientific journal)

Subsequence matching is a basic problem in the field of data stream mining. In recent years, there has been significant research effort spent on efficiently finding subsequences similar to a query sequence. Another challenging issue in relation to subsequence matching is how we identify common local patterns when both sequences are evolving. This problem arises in trend detection, clustering, and outlier detection. Dynamic time warping (DTW) is often used for subsequence matching and is a powerful similarity measure. However, the straightforward method using DTW incurs a high computation cost for this problem. In this paper, we propose a one-pass algorithm, CrossMatch, that achieves the above goal. CrossMatch addresses two important challenges: (1) how can we identify common local patterns efficiently without any omission? (2) how can we find common local patterns in data stream processing? To tackle these challenges, CrossMatch incorporates three ideas: (1) a scoring function, which computes the DTW distance indirectly to reduce the computation cost, (2) a position matrix, which stores starting positions to keep track of common local patterns in a streaming fashion, and (3) a streaming algorithm, which identifies common local patterns efficiently and outputs them on the fly. We provide a theoretical analysis and prove that our algorithm does not sacrifice accuracy. Our experimental evaluation and case studies show that CrossMatch can incrementally discover common local patterns in data streams within constant time (per update) and space.

DOI： 10.1007/s00778-012-0289-3

Event Pattern Queries on Probabilistic Event Streams Reviewed

Sho Kato, Yoshiharu Ishikawa

DBSJ Journal Vol. 12 ( 1 ) page： 55-60 2013.6

Language：Japanese Publishing type：Research paper (scientific journal)

Complex event processing (CEP) is a task to detect high-level events from a large volume of stream data. In this paper, we focus on CEP for probabilistic event streams in which each event is assigned its occurrence probability. We propose two types of pattern query semantics to get a group of matches for a given regular expression pattern. A group of matches represents a semantic unit for considering high-level events.

Query Processing in Moving Robot Databases

Kento Sugiura, Arata Hayashi, Yoshiharu Ishikawa

Technical Report of IEICE Vol. 113 ( 150 ) page： 145-150 2013.7

Similarity Queries on Gaussian Distributions

Tingting Dong, Chuan Xiao, Yoshiharu Ishikawa

IPSJ SIG Technical Report Vol. 2013-DBS-157 ( 32 ) page： 1-6 2013.7

Processing Probabilistic Range Queries over Gaussian-based Uncertain Data Reviewed

Tingting Dong, Chuan Xiao, Xi Guo, Yoshiharu Ishikawa

Processing Probabilistic Range Queries over Gaussian-based Uncertain Data page： 410-428 2013.8

Language：English Publishing type：Research paper (scientific journal)

Probabilistic range query is an important type of query in the area of uncertain data management. A probabilistic range query returns all the objects within a specific range from the query object with a probability no less than a given threshold. In this paper we assume that each uncertain object stored in the databases is associated with a multi-dimensional Gaussian distribution, which describes the probability distribution that the object appears in the multi-dimensional space. A query object is either a certain object or an uncertain object modeled by a Gaussian distribution. We propose several filtering techniques and an R-tree-based index to efficiently support probabilistic range queries over Gaussian objects. Extensive experiments on real data demonstrate the efficiency of our proposed approach.

DOI： 10.1007/978-3-642-40235-7_24

曖昧な移動軌跡に対する範囲問合せ

早矢仕新, 杉浦健人, 董ていてい, 石川佳治

第12回情報科学技術フォーラム（FIT 2013）講演論文集 page： D-013 2013.9

オントロジーに基づくLBSN上でのイベント検出

稲葉鉄平, 高橋正和, 簗井美咲, 石川佳治

第12回情報科学技術フォーラム（FIT 2013）講演論文集 page： D-030 2013.9

Collocation Extraction Using a PMI-Based Association Measure for Dependency Tree Pattern Reviewed

Hiroki Takayama, Yoshihide Kato, Tomohiro Ohno, Shigeki Matsubara, Yoshiharu Ishikawa

Proceedings of the 10th International Symposium on Natural Language Processing (SNLP 2013) page： 136-141 2013.10

Language：English Publishing type：Research paper (scientific journal)

In this paper, we propose a method of automatically extracting collocations from a dependency treebank. This method obtains sequences of words connected with dependency relations by extracting tree patterns from a dependency treebank. For the tree patterns, the method applies an association measure which is based on pointwise mutual information(PMI) and selects tree patterns corresponding to collocations. Our method can obtain discontinuous collocations which are made up of three or more words. We conducted an experiment using ACL Anthology Corpus. The experimental result shows that this method is effective for extracting discontinuous collocations which consist of three or more words.

Clustering Editors of Wikipedia by Editor's Biases Reviewed

Akira Nakamura, Yu Suzuki, Yoshiharu Ishikawa

Proceedings of the 2013 IEEE/WIC/ACM International Conference on Web Intelligence (WI 2013) page： 351-358 2013.11

Language：English Publishing type：Research paper (scientific journal)

Wikipedia is an Internet encyclopedia where any user can edit articles. Because editors act on their own judgments, editors' biases are reflected in edit actions. When editors' biases are reflected in articles, the articles have low credibility. However, it is difficult for users to judge which parts in articles have biases. In this paper, we propose a method of clustering editors by editors' biases for the purpose that we distinct texts' biases by using editors' biases and aid users to judge the credibility of each description. If each text is distinguished such as by colors, users can utilize it for the judgments of the text credibility. Our system makes use of the relationships between editors: agreement and disagreement. We assume that editors leave texts written by editors that they agree with, and delete texts written by editors that they disagree with. In addition, we can consider that editors who agree with each other have similar biases, and editors who disagree with each other have different biases. Hence, the relationships between editors enable to classify editors by biases. In experimental evaluation, we verify that our proposed method is useful in clustering editors by biases. Additionally, we validate that considering the dependency between editors improves the clustering performance.

オントロジーを利用したLBSN基盤フレームワークの設計

稲葉鉄平, 簗井美咲, 高橋正和, 石川佳治

第6回データ工学と情報マネジメントに関するフォーラム（DEIM 2014） page： E4-5 2014.3

パーティクル表現を用いた曖昧位置情報に対する空間問合せ処理

早矢仕新, 杉浦健人, 董ていてい, 石川佳治

第6回データ工学と情報マネジメントに関するフォーラム（DEIM 2014） page： E4-6 2014.3

人気経路の推薦のための大規模移動軌跡データ処理

姜仁河, 杉山武至, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 1N-3 2014.3

確率的ストリームにおけるグループを用いたパターン問合せ

杉浦健人, 早矢仕新, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 3N-5 2014.3

Wikipedia のノートページにおける編集者の重要度算出手法

近藤弘隆, 鈴木優, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 4M-9 2014.3

オントロジーを利用したイベント処理システムの提案

高橋正和, 簗井美咲, 稲葉鉄平, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 5N-1 2014.3

LBSNオントロジーの設計

簗井美咲, 高橋正和, 稲葉鉄平, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 5N-3 2014.3

参加型センシングにおけるプライバシー保護手法

趙セイ, 董テイテイ, 石川佳治

情報処理学会第76回全国大会講演論文集 page： 5N-7 2014.3

Efficient Processing of Graph Similarity Queries with Edit Distance Constraints Reviewed

Xiang Zhao, Chuan Xiao, Xuemin Lin, Wei Wang, Yoshiharu Ishikawa

The VLDB Journal Vol. 22 ( 6 ) page： 727-752 2014.2

Probabilistic Range Querying over Gaussian Objects Reviewed

Tingting Dong, Chuan Xiao, Yoshiharu Ishikawa

IEICE Transactions on Information Systems (accepted for publication) Vol. E97-D ( 4 ) page： 694-704 2014.4

Language：English Publishing type：Research paper (scientific journal)

Probabilistic range query is an important type of query in the area of uncertain data management. A probabilistic range query returns all the data objects within a specific range from the query object with a probability no less than a given threshold. In this paper, we assume that each uncertain object stored in the database is associated with a multi-dimensional Gaussian distribution, which describes the probability distribution that the object appears in the multi-dimensional space. A query object is either a certain object or an uncertain object modeled by a Gaussian distribution. We propose several filtering techniques and an R-tree-based index to efficiently support probabilistic range queries over Gaussian objects. Extensive experiments on real data demonstrate the efficiency of our proposed approach.

DOI： 10.1587/transinf.E97.D.694

Research Trend and Future Prospects for Large-Scale Data Analytics Invited Reviewed

Yoshiharu Ishikawa

IEICE Transactions on Information and Vol. J97-D ( 4 ) page： 718-728 2014.4

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

Facing the age of big data, data analytics, in which sophisticated analysis is performed on large amouts of data, is the focus on attention. In this paper, we survey the current trend of research and development of data analytics and describe the future prospects. First, we classify various approaches for data analytics and then explain how DBMSs are extended for data analytics. Moreover, we describe how machine learning facilities are incoporated in DBMSs and how DBMSs are used as simulation engines. Then, we compare parallel DBMSs and MapReduce from the viewpoint of data analytics and mention system architecture issues. Finally, we present some interesting extentions of MapReduce for data analytics and then present the outlook for the future.

Monitoring Query Processing in Mobile Robot Databases Reviewed

Kento Sugiura, Arata Hayashi, Tingting Dong, Yoshiharu Ishikawa

Proceedings of the Third International Workshop on Spatial Information Modeling, Management and Mining (SIM3 2014) page： 271-282 2014.4

Wikipediaにおける単語の順序を考慮した編集の差し戻し検知手法

近藤弘隆，中村晃，鈴木優，石川佳治

情報処理学会研究報告 Vol. 2014-DBS-159 ( 2 ) page： 7-12 2014.8

確率的データストリームにおけるパターン問合せのグループ化

杉浦健人，石川佳治，佐々木勇和

情報処理学会研究報告 Vol. 2014-DBS-159 ( 20 ) page： 113-118 2014.8

行動オントロジによるセンサデータからの複合イベント検出について

佐々木勇和，簗井美咲，高橋正和，杉浦健人，石川佳治

第13回情報科学技術フォーラム（FIT 2014）講演論文集 page： D-031 2014.9

参加型センシングのための空間データベース問合せ処理

趙セイ，杉浦健人，姜仁河，佐々木勇和，石川佳治

第13回情報科学技術フォーラム（FIT 2014）講演論文集 page： D-033 2014.9

LBSNオントロジの構築

簗井美咲，高橋正和，佐々木勇和，石川佳治

第13回情報科学技術フォーラム（FIT 2014）講演論文集 page： D-042 2014.9

RDFストリーム上での複合イベント検出

高橋正和，簗井美咲，佐々木勇和，石川佳治

第13回情報科学技術フォーラム（FIT 2014）講演論文集 page： D-044 2014.9

A Slide Element Retrieval Method for Presentation Reuse

Jie Zhang, Chuan Xiao, Toyohide Watanabe, Yoshiharu Ishikawa

電子情報通信学会技術研究報告 Vol. 114 ( 204 ) page： 69-74 2014.9

Content-Based Element Search for Presentation Slide Reuse Reviewed

Jie Zhang, Chuan Xiao, Toyohide Watanabe, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. 97-D ( 10 ) page： 2685-2696 2014.10

Language：English Publishing type：Research paper (scientific journal)

Presentation slide composition is an important job for knowledge workers. Instead of starting from scratch, users tend to make new presentation slides by reusing existing ones. A primary challenge in slide reuse is to select desired materials from a collection of existing slides. The state-of-the-art solution utilizes texts and images in slides as well as file names to help users to retrieve the materials they want. However, it only allows users to choose an entire slide as a query but does not support the search for a single element such as a few keywords, a sentence, an image, or a diagram. In this paper, we investigate content-based search for a variety of elements in presentation slides. Users may freely choose a slide element as a query. We propose different query processing methods to deal with various types of queries and improve the search efficiency. A system with a user-friendly interface is designed, based on which experiments are performed to evaluate the effectiveness and the efficiency of the proposed methods.

DOI： 10.1587/transinf.2014EDP7023

Managing Presentation Slides with Reused Elements Reviewed

Jie Zhang, Chuan Xiao, Sheng Hu, Toyohide Watanabe, Yoshiharu Ishikawa

Proceedings of the 6th International Conference on Computer Technology and Development (ICCTD 2014) page： ? 2014.11

Language：English

Slide presentations have become a ubiquitous tool for business and educational purposes. Instead of starting from scratch, slide composers tend to make new presentation slides by reusing materials from existing slides. Understanding how slide elements are copied from one presentation file to another and how presentation files are related to each other are difficult tasks.
In this paper, we investigate the management of multiple presentation files based on reused slide elements.We develop techniques to detect text and images that have been reused across multiple presentation files. Interactive visualization methods are proposed to facilitate understanding the process by which these elements are reused and the relationship between the files that use them. A system with a user-friendly interface is designed, based on which experiments are performed to evaluate the effectiveness of the proposed methods.

Detecting Reused Elements in Presentation Slides Reviewed

Jie Zhang, Chuan Xiao, Toyohide Watanabe, Yoshiharu Ishikawa

Proceedings of 2014 International Conference on Computer Engineering (ICOCE 2014) page： ? 2014.11

Language：English

Slide presentations have become a ubiquitous tool for business and educational purposes. Instead of starting from scratch, slide composers tend to make new presentation slides by browsing existing slides and reusing materials from them. In this paper, we investigate the problem of reused element detection in presentation slides. We develop respective techniques to identify both textual and visual elements that have been reused across multiple presentation files. Experiments are performed to evaluate the effectiveness of the proposed methods.

意味的な複合イベント処理を可能とするイベントベースについて

石川佳治，佐々木勇和，簗井美咲，高橋正和，杉浦健人

情報処理学会研究報告 page： ? 2014.11

確率的データストリームにおけるパターン照合結果のグループ化

杉浦健人, 佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： B3-3 2015.3

共同編集コンテンツにおける編集者関係グラフに基づいた編集者の質予測

中村晃, 鈴木優, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： D4-3 2015.3

LBSNのための汎用的なオントロジフレームワーク構築

簗井美咲, 高橋正和, 佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： F6-2 2015.3

KL情報量に基づいたガウス分布の類似検索

董テイテイ, 石川佳治, 肖川

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： A6-3 2015.3

多階層のカテゴリ分類を用いたスカイライン経路検索について

佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： A6-4 2015.3

参加型センシングのためのタスク割当て手法

趙菁, 姜仁河, 董テイテイ, 佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： C6-5 2015.3

密度に基づく意味的な軌跡パターンの発見

姜仁河, 趙菁, 董テイテイ, 佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： C8-4 2015.3

オントロジとデータベース技術を活用した複合イベント処理システム

高橋正和, 簗井美咲, 佐々木勇和, 石川佳治

第7回データ工学と情報マネジメントに関するフォーラム（DEIM 2015）論文集 page： C8-4 2015.3

Twitterにおけるユーザごとの意見変化抽出手法

近藤弘隆, 鈴木優, 石川佳治

情報処理学会第77回全国大会講演論文集 page： 2M-04 2015.3

時空間データ分析のためのSpatialHadoopの拡張

瀧本祥章, 杉浦健人, 佐々木勇和, 石川佳治

情報処理学会第77回全国大会講演論文集 page： 4N-01 2015.3

Content Reuse Detection in Text Documents

Pei Wang, Chuan Xiao, Yoshiharu Ishikawa

情報処理学会第77回全国大会講演論文集 page： 5N-04 2015.3

AEDSMS: Automotive Embedded Data Stream Management System Reviewed

Akihiro Yamaguchi, Yukikazu Nakamoto, Kenya Sato, Yoshiharu Ishikawa, Yousuke Watanabe, Shinya Honda, Hiroaki Takada

Proceedings of the 31st International Conference on Data Engineering (ICDE 2015), page： 1292-1303 2015.4

Language：English

Data stream management systems (DSMSs) are useful for the management and processing of continuous data at a high input rate with low latency. In the automotive domain, embedded systems use a variety of sensor data and communications from outside the vehicle to promote autonomous and safe driving. Thus, the software developed for these systems must be capable of handling large volumes of data and complex processing. At present, we are developing a platform for the integration and management of data in an automotive embedded system using a DSMS. However, compared with conventional DSMS fields, we have encountered new challenges such as precompiling queries when designing automotive systems (which demands time predictability), distributed stream processing in in-vehicle networks, and real-time scheduling and sensor data fusion by stream processing. Therefore, we developed an automotive embedded DSMS (AEDSMS) to address these challenges. The main contributions of the present study are: (1) a clear understanding of the challenges faced when introducing DSMSs into the automotive field; (2) the development of AEDSMS to tackle these challenges; and (3) an evaluation of AEDSMS during runtime using a driving assistance application.

DOI： 10.1109/ICDE.2015.7113377

Grouping Methods for Pattern Matching in Probabilistic Data Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa, Yuya Sasaki

Proceedings of the 20th International Conference on Database Systems for Advanced Applications (DASFAA 2015) 2015.4

Language：English

In recent years, complex event processing has attracted considerable interest in research and industry.Pattern matching is used to find complex events in data streams. In probabilistic data streams, however, the system may find multiple matches in a given time interval. This may result in inappropriate matches, because multiple matches may correspond to a single event. We therefore propose grouping methods of matches for probabilistic data streams, and call such merged matches a group. We describe the definitions and generation methods of groups, propose an efficient approach for calculating an occurrence probability of a group, and compare the proposed approach with a naive one by experiment. The results demonstrate the properties and effectiveness of the proposed method.

DOI： 10.1007/978-3-319-18120-2_6

共同執筆コンテンツにおける単語の起源追跡 Reviewed

中村晃，鈴木優，石川佳治

情報処理学会論文誌データベース（TOD） Vol. 8 ( 2 ) page： 43-56 2015.6

確率的データストリームにおけるパターン照合結果の時間的重複に基づくグループ化

杉浦健人, 石川佳治, 佐々木勇和

情報処理学会研究報告 Vol. 2015-DBS-161 ( 7 ) page：（番号なし） 2015.8

空間クラウドソーシングのための多様性を考慮したタスク割り当て手法

趙セイ, 石川佳治, 肖川, 董テイテイ, 佐々木勇和

情報処理学会研究報告 Vol. 2015-DBS-161 ( 8 ) page：（番号なし） 2015.8

Detecting Reused Contents in Text Documents

Pei Wang, Chuan Xiao, Yoshiharu Ishikawa

page： 3C-2 2015.9

シミュレーションデータの分析管理のためのデータウェアハウスについて

石川佳治, 王元元, 董テイテイ, 杉浦健人, 佐々木勇和

第14回情報科学技術フォーラム (FIT 2015) 講演論文集 page： 3D-2 2015.9

複数ドメインのデータストリームにおける意味的なイベント検出について

佐々木勇和, 石川佳治, 杉浦健人

第14回情報科学技術フォーラム (FIT 2015) 講演論文集 page： 3D-3 2015.9

Reverse Direction-Based Surrounder Queries Reviewed

Xi Guo, Yoshiharu Ishikawa, Aziguli Wulamu, Yonghong Xie

Proceedings of the 17th Asia-Pacific Web Conference (APWeb 2015) page： 280-291 2015.9

Language：English

This paper proposes a new spatial query called the reverse direction-based surrounder (RDBS) query, which retrieves a user who is seeing a point of interest (POI) as one of their direction-based surrounders (DBSs). According to a user, one POI can be dominated by a second POI if the POIs are directionally close and the first POI is farther from the user than the second is. Two POIs are directionally close if their included angle with respect to the user is smaller than an angular threshold, θ. If a POI cannot be dominated by another POI, it is a DBS of the user. We also propose an extended query called the competitor RDBS query. POIs that share the same RDBSs with another POI are defined as competitors of that POI. We design algorithms to answer the RDBS queries and competitor queries. The experimental results show that the proposed algorithms can answer the queries efficiently.

DOI： 10.1007/978-3-319-25255-1_23

A Density-based Approach for Mining Movement Patterns from Semantic Trajectories Reviewed

Renhe Jiang, Jing Zhao, Tingting Dong, Yoshiharu Ishikawa, Chuan Xiao, Yuya Sasaki

Proceedings of IEEE TENCON 2015 - IEEE Region 10 Conference page：（なし） 2015.11

Language：English

In this paper, we study the problem of discovering all movement patterns from semantic trajectory databases. We propose a two-step method to solve this problem efficiently. We first retrieve frequent movement patterns of categories from the transformed database of sequential categories, and then cluster dense trajectories in a growth-type way for all movement patterns. Moreover, we define a new metric distance function on trajectories. We also use M-tree to cluster trajectories more efficiently. Our experimental results demonstrate the efficiency of the proposed method.

An Automatic Video Reinforcing System based on Popularity Rating of Scenes and Level of Detail Controlling Reviewed

Yuanyuan Wang, Kazutoshi Sumiya, Yukiko Kawai, Yoshiharu Ishikawa

Proceedings of the 11th IEEE International Workshop on Multimedia Information Processing and Retrieval (IEEE-MIPR 2015) page： 529-534 2015.12

Language：English

With the advance of video-on-demand (VOD) services such as Netfix, users are able to watch many kinds of videos anytime and anywhere. While watching a video, recently, users often search related information about it through the Web by using mobile PC. However, users cannot satisfactorily understand and enjoy it because the video keeps playing when they search about it. It is necessary to detect various questions of the video to supplement their related information about each scene for automatic search. However, only one video includes various topics of each scene, furthermore, viewers have different levels of knowledge. Therefore, we have developed a novel automatic video reinforcing system, called TV-Binder, it generates new video contents from one video stream related to viewers' interests and knowledge by adding other related contents (i.e., YouTube videos, images or maps) and by removing unnecessary original scenes, based on topics of each scene. As a result, viewers can satisfy and joyfully watch modified video contents without searching anything. At first, our system extract topics and detect their scenes of a video stream by using closed captions. The system then searches other necessary contents and determines unwanted original scenes based on popularity rating of each original scene and level of detail (LOD) controlling under time pressure. Through this, TVBinder can automatically generate video contents are classified into four quadrants by two axes; one is digest and detailed videos, the other one is videos for experts with knowledge about particular topics and ordinary viewers without special knowledge. In this paper, we discuss our automatic video reinforcing system and an evaluation of its effectiveness.

k-Expected Nearest Neighbor Search over Gaussian Objects Reviewed

Tingting Dong, Ishikawa Yoshiharu, Chuan Xiao, Jing Zhao

Proceedings of the 4th International Conference on Network and Computing Technology (ICNCT 2015) page： 1-11 2015.12

Language：English

Probabilistic location information has been attracting more and more attention due to the advances in computing devices and technologies, and has become an important research topic in recent years. In particular, Gaussian distribution is frequently used to represent probabilistic location information. On the other hand, as one of the commonest queries over location information, the distance-based nearest neighbor search, which finds closest objects to a given query point, has extensive applications in various areas. There have been considerable efforts made to extend nearest neighbor search over traditional location information to probabilistic location information. An example is the expected distance, which defines the distance over probabilistic location information. Following this trend, in this paper, we assume that the closeness between objects represented by Gaussian distributions are measured by their expected distance and consider the problem of k-expected nearest neighbor search. We analyze properties of expected distance on Gaussian distributions mathematically and derive its lower bound and upper bound. Based on our analysis, we propose three novel approaches to efficiently solve this problem. The efficiency of our approaches is demonstrated through extensive experiments.

Top-k Similarity Search over Gaussian Distributions Based on KL-Divergence Reviewed

Tingting Dong, Yoshiharu Ishikawa, Chuan Xiao

Journal of Information Processing Vol. 24 ( 1 ) page： 152-163 2016.1

Language：English Publishing type：Research paper (scientific journal)

The problem of similarity search is a crucial task in many real-world applications such as multimedia databases, data mining, and bioinformatics. In this work, we investigate the similarity search on uncertain data modeled in Gaussian distributions. By employing Kullback-Leibler divergence (KL-divergence) to measure the dissimilarity
between two Gaussian distributions, our goal is to search a database for the top-k Gaussian distributions similar to a given query Gaussian distribution. Especially, we consider non-correlated Gaussian distributions, where there are no correlations between dimensions and their covariance matrices are diagonal. To support query processing, we
propose two types of novel approaches utilizing the notions of rank aggregation and skyline queries. The efficiency and effectiveness of our approaches are demonstrated through a comprehensive experimental performance study.

DOI： 10.2197/ipsjjip.24.152

An Automatic Video Reinforcing System for TV Programs Using Semantic Metadata Reviewed

Yuanyuan Wang, Daisuke Kitamura, Yukiko Kawai, Kazutoshi Sumiya, Yoshiharu Ishikawa

International Journal of Multimedia Data Engineering and Management (IJMDEM) Vol. 7 ( 1 ) page： 1-21 2016.1

時間帯を考慮したパーソナライズ目的地予測

瀧本祥章, 西田京介, 遠藤結城, 戸田浩之, 澤田宏, 石川佳治

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： H1-2 2016.2

多階層のカテゴリ分類を用いたSkySR検索の効率化について

佐々木勇和，石川佳治

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： A2-2 2016.2

シミュレーションデータウエアハウスにおける災害情報の統合分析

趙菁，石川佳治，杉浦健人，王元元，佐々木勇和, 瀧本祥章

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： A2-3 2016.2

Wikipediaのカテゴリを用いた編集者の得意分野特定

近藤弘隆，鈴木優，石川佳治

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： C3-5 2016.3

Efficient Autocompletion with Error Tolerance

Sheng Hu, Chuan Xiao, Yoshiharu Ishikawa

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： D4-1 2016.3

確率的データストリームにおける情報利得に基づいたパターン照合手法

杉浦健人，石川佳治，佐々木勇和

第8回データ工学と情報マネジメントに関するフォーラム (DEIM 2016) page： A7-2 2016.3

Simulation Data Warehouse for Integration and Analysis of Disaster Information Reviewed

Jing Zhao, Kento Sugiura, Yuanyuan Wang, Yoshiharu Ishikawa

Journal of Disaster Research Vol. 11 ( 2 ) page： 255-265 2016.3

次世代ライフログのための行動オントロジを用いた意味的な複合イベント処理について

橋本聡和, 佐々木勇和，石川佳治, 中村亮

情報処理学会第78回全国大会講演論文集 page： 4L-01 2016.3

RDBを用いた複合イベント処理システムの開発

金山貴紀, 石川佳治, 杉浦健人, 佐々木勇和

情報処理学会第78回全国大会 page： 4L-02 2016.3

生活環境QOLデータの可視化・分析システムの開発

石川佳治, 鈴木優, 王元元, 佐々木勇和, 董テイテイ

電子情報通信学会総合大会 page： D-4-6 2016.3

BEVA: An Efficient Query Processing Algorithm for Error Tolerant Autocompletion Reviewed

Xiaoling Zhou, Jianbin Qin, Chuan Xiao, Wei Wang, Xuemin Lin, Yoshiharu Ishikawa

ACM Transactions on Database Systems (TODS), Vol. 41 ( 1 ) 2016.4

Managing Presentation Slides with Reused Elements Reviewed

Jie Zhang, Chuan Xiao, Sheng Hu, Toyohide Watanabe, Yoshiharu Ishikawa

International Journal of Information and Education Technologies (IJIET) Vol. 6 ( 3 ) page： 170-177 2016.4

Dynamic Mapping of Dense Geo-Tweets and Web Pages based on Spatio-Temporal Analysis Reviewed

Yuanyuan Wang, Goki Yasui, Yukiko Kawai, Toyokazu Akiyama, Kazutoshi Sumiya, Yoshiharu Ishikawa

The 31st ACM/SIGAPP Symposium on Applied Computing (SAC 2016) page： 1170-1173 2016.4

Local Similarity Search for Unstructured Text Reviewed

Pei Wang, Chuan Xiao, Jianbin Qin, Wei Wang, Xiaoyang Zhang, Yoshiharu Ishikawa

The 2016 ACM SIGMOD International Conference on Management of Data 2016.6

TweeVist: A Geo-Tweet Visualization System for Web based on Spatio-Temporal Events Reviewed

Yuanyuan Wang, Yukiko Kawai, Kazutoshi Sumiya, Yoshiharu Ishikawa

The 15th IEEE/ACIS International Conference on Computer and Information Science (ICIS 2016) page： 729-734 2016.6

Frequent Subgraph Mining Based on Pregel Reviewed

Xiang Zhao, Yifan Chen, Chuan Xiao, Yoshiharu Ishikawa, Jiuyang Tang

The Computer Journal Vol. 59 ( 8 ) page： 1113-1128 2016.8

時空間データウェアハウスにおける差分演算について

趙セイ, 石川佳治, 杉浦健人, 脇田佑希子

第15回情報科学技術フォーラム (FIT 2016) page： 2D-4 2016.9

オントロジを用いた行動イベント分析

中村亮, 石川佳治, 杉浦健人, 脇田佑希子, 佐々木勇和

第15回情報科学技術フォーラム (FIT 2016) page： 6C-2 2016.9

不完全な道路ネットワークを用いたマップマッチングおよび道路ネットワークの補間手法の提案

余家豪, 佐々木勇和, 石川佳治

第15回情報科学技術フォーラム (FIT 2016) page： 7C-1 2016.9

ジオタグ付き写真を用いた意味的な移動軌跡の分析

瀧本祥章, 石川佳治, 杉浦健人, 脇田佑希子

第15回情報科学技術フォーラム (FIT 2016) page： 7C-3 2016.9

確率的データストリームにおける情報利得を用いたパターン照合手法

杉浦健人, 石川佳治

情報処理学会データベースシステム・情報基礎とアクセス技術合同研究会 page： 2016-DBS-163(5) 2016.9

k-Expected Nearest Neighbor Search over Gaussian Objects Reviewed

Tingting Dong, Yoshiharu Ishikawa, Chuan Xiao, Jing Zhao

Journal of Computers (JCP) Vol. 12 ( 2 ) page： 105-115 2017.3

時空間データ分析のための差分ヒストグラム構築手法

趙セイ, 石川佳治, 杉浦健人, 脇田佑希子

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： G1-2 2017.3

確率的データストリームにおける情報利得を用いたTop-kパターン照合手法

杉浦健人, 石川佳治

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： G3-3 2016.3

略記問合せに対する効率的な問合せ自動補完

胡晟, 肖川, 石川佳治

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： G4-4 2017.3

ライフログサービスのためのオントロジに基づく行動イベント処理

中村亮, 石川佳治, 杉浦健人, 脇田佑希子

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： I5-1 2016.3

不完全な道路ネットワークにおけるマップマッチングとクラスタリング手法を用いた道路セグメントの補間手法の提案

余家豪, 佐々木勇和, 石川佳治

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： A5-5 2017.3

ジオタグ付き写真の被写体を考慮した意味的な移動軌跡の分析

瀧本祥章, 杉浦健人, 石川佳治

第9回データ工学と情報マネジメントに関するフォーラム (DEIM 2017) page： H7-5 2017.3

配列指向DBMSを用いた避難シミュレーションデータの格納と分析

河井悠佑, 杉浦健人, 趙セイ, 石川佳治

情報処理学会第79回全国大会 page： 1L-03 2017.3

Event Calculusに基づく複合イベント処理について

金山貴紀, 杉浦健人, 石川佳治

情報処理学会第79回全国大会 page： 1L-05 2017.3

オントロジに基づく移動軌跡の意味的な拡張と検索

勝田健斗, 中村亮, 瀧本祥章, 石川佳治

情報処理学会第79回全国大会 page： 2K-09 2017.3

都市・国土環境分析のためのレジリエンス・サステナビリティ評価ワークベンチの開発

石川佳治，脇田佑希子, 杉浦健人, 杉本賢二, 加藤博和

電子情報通信学会総合大会 page： D-4-2 2017.3

Grouping Methods for Pattern Matching over Probabilistic Data Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa, Yuya Sasaki

IEICE Transactions on Information and Systems Vol. E100-D ( 4 ) page： 718-729 2017.4

Language：English Publishing type：Research paper (scientific journal)

As the development of sensor and machine learning technologies has progressed, it has become increasingly important to detect patterns from probabilistic data streams. In this paper, we focus on complex event processing based on pattern matching. When we apply pattern matching to probabilistic data streams, numerous matches may be detected at the same time interval because of the uncertainty of data. Although existing methods distinguish between such matches, they may derive inappropriate results when some of the matches correspond to the real-world event that has occurred during the time interval. Thus, we propose two grouping methods for matches. Our methods output groups that indicate the occurrence of complex events during the given time intervals. In this paper, first we describe the definition of groups based on temporal overlap, and propose two grouping algorithms, introducing the notions of complete overlap and single overlap. Then, we propose an efficient approach for calculating the occurrence probabilities of groups by using deterministic finite automata that are generated from the query patterns. Finally, we empirically evaluate the effectiveness of our methods by applying them to real and synthetic datasets.

DOI： 10.1587/transinf.2016DAP0014

Time-Aware Personalized Destination Prediction Reviewed

Yoshiaki Takimoto, Kyosuke Nishida, Yuki Endo, Hiroyuki Toda, Hiroshi Sawada, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J100-D ( 4 ) page： 472-484 2017.4

Top-k Pattern Matching Using an Information-theoretic Criterion over Probabilistic Data Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa

Proceedings of APWeb-WAIM Joint Conference on Web and Big Data 2017 page： 511-526 2017.7

Language：English

As the development of data mining technologies for sensor data streams, more sophisticated methods for complex event processing are demanded. In the case of event recognition, since event recognition results may contain errors, we need to deal with the uncertainty of events. We therefore consider probabilistic event data streams with occurrence probabilities of events, and develop a pattern matching method based on regular expressions. In this paper, we first analyze the semantics of pattern matching over non-probabilistic data streams, and then propose the problem of top-k pattern matching over probabilistic data streams. We introduce the use of an information-theoretic criterion to select appropriate matches as the result of pattern matching. Then, we present an efficient algorithm to detect top-k matches, and evaluate the effectiveness of our approach using real and synthetic datasets.

DOI： 10.1007/978-3-319-63579-8_39

Extraction of Frequent Patterns Based on Users' Interests from Semantic Trajectories with Photographs Reviewed

Yoshiaki Takimoto, Kento Sugiura, Yoshiharu Ishikawa

Proceedings of the 21st International Database Engineering & Applications Symposium (IDEAS 2017) page： 219-227 2017.7

Language：English

Along with the popularization of location-based social networking (LBSN), semantic trajectories, which are trajectories with additional information such as photographs and texts, are increasing, and their utilization is required. We consider frequent pattern extraction as applicable to analysis of semantic trajectories and extraction of regions of interest (ROIs). In this research, we propose SimDBSCAN, which considers both spatial density and similarity of points, by extending DBSCAN, which uses density-based clustering, in order to capture users' interests. Since SimDBSCAN identifies points that are interested in the same object in the neighborhood as ROIs, it is possible to detect not only known ROIs such as tourist sites but also unknown ROIs. In this paper, we explain the algorithm of SimDBSCAN and present the experimental results using photographs collected from Flickr. The experiments show that useful ROIs and patterns can be extracted by the proposed method.

DOI： 10.1145/3105831.3105870

Reverse Direction-based Surrounder Queries for Mobile Recommendations Reviewed

Xi Guo, Yoshiharu Ishikawa, Yonghong Xie, Aziguli Wulamu

World Wide Web Journal Vol. 20 ( 5 ) page： 885-913 2017.9

Language：English Publishing type：Research paper (scientific journal)

This paper proposes a new spatial query called a reverse direction-based surrounder (RDBS) query, which retrieves a user who is seeing a point of interest (POI) as one of their direction-based surrounders (DBSs). According to a user, one POI can be dominated by a second POI if the POIs are directionally close and the first POI is farther from the user than the second is. Two POIs are directionally close if their included angle with respect to the user is smaller than an angular threshold theta. If a POI cannot be dominated by another POI, it is a DBS of the user. We also propose an extended query called competitor RDBS query. POIs that share the same RDBSs with another POI are defined as competitors of that POI. We design algorithms to answer the RDBS queries and competitor queries. The experimental results show that the proposed algorithms can answer the queries efficiently.

DOI： 10.1007/s11280-016-0422-0

逆最近傍問合せに基づくデマンドヒートマップの連続的な更新手法

李セイ, 石川佳治, 趙セイ, 杉浦健人

第16回情報科学技術フォーラム (FIT 2017) 論文集 page： D-012 2017.9

Event Calculusに基づく複合イベント処理について

金山貴紀, 石川佳治, 杉浦健人

第16回情報科学技術フォーラム (FIT 2017) 論文集 page： D-019 2017.9

ビッグデータへの取り組みと周辺領域との融合

小口正人, 中野美由紀, 石川佳治, 木俵豊

電子情報通信学会誌 Vol. 100 ( 10 ) page： 1059 2017.10

An Efficient Algorithm for Location-Aware Query Autocompletion Reviewed

Sheng Hu, Chuan Xiao, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E101-D ( 1 ) page： 181-192 2018.1

RDBと連携したイベント計算による複合イベント処理

金山貴紀, 石川佳治, 杉浦健人

第10回データ工学と情報マネジメントに関するフォーラム (DEIM 2018) 論文集 page： E1-4 2018.3

大量な映像における高速な動的場面の分析と検索

胡晟, 劉健全, 西村祥治, 石川佳治

第10回データ工学と情報マネジメントに関するフォーラム (DEIM 2018) 論文集 page： A3-3 2018.3

ネットワーク上の軌跡データに対する時間制約付き二点間経路の列挙

小出智士, 吉村貴克, 肖川, 石川佳治

第10回データ工学と情報マネジメントに関するフォーラム (DEIM 2018) 論文集 page： H5-1 2018.3

少数ユーザの移動履歴を考慮した大規模な集計データからの人流推定

河井悠佑, 田中佑典, 戸田浩之, 石川佳治

第10回データ工学と情報マネジメントに関するフォーラム (DEIM 2018) page： C5-3 2018.3

配列DBMSにおける時空間データの差分分析について

趙セイ, 石川佳治, 河井悠佑, 杉浦健人

第10回データ工学と情報マネジメントに関するフォーラム (DEIM 2018) 論文集 page： C6-3 2018.3

配列DBMSにおける空間スキャン統計量の計算手法

安田健人，河井悠佑, 趙セイ，杉浦健人，石川佳治

情報処理学会全国大会講演論文集 page： 4L-5 2018.3

Context-Sensitive Query Auto-Completion with Knowledge Base

Yaobin Hu, Chuan Xiao, Yoshiharu Ishikawa

page： P5-2 2018.3

RDBの構造を考慮したデータベースからの学習手法について

志村薫，石川佳治, 杉浦健人

情報処理学会全国大会講演論文集 page： 6L-6 2018.3

大規模データ分析のための可視化手法に関する検討

野田昌太郎，河井悠佑, 趙セイ，杉浦健人，石川佳治

情報処理学会全国大会講演論文集 page： 6L-7 2018.3

An Analysis Technique of Evacuation Simulation Using an Array DBMS Reviewed

Yusuke Kawai, Jing Zhao, Kento Sugiura, Yoshiharu Ishikawa, Yukiko Wakita

Journal of Disaster Research Vol. 13 ( 2 ) page： 338-346 2018.3

Language：English Publishing type：Research paper (scientific journal)

Today, large-scale simulations are thriving because of the increase of computating performance and storage capacity. Understanding the results of these simulations is not easy, and hence, support for interactive and exploratory analysis is becoming more important. This study focuses on spatio-temporal simulations and attempts to develop an analysis technology to support them. It uses a database system for supporting interactive analysis of large-scale data.
Since the data gained via spatio-temporal simulations is not suitable for management in a relational DBMS (RDBMS), this study uses an array DBMS, a type of DBMS that has been garnering increased attention in recent years. An array DBMS is designed for the management of large-scale array data; it provides a logical model for array data, yet it also supports efficient query processing. SciDB is used as our specific array DBMS in this paper.
This study targets disaster evacuation simulation data and demonstrates via experimentation that the query-processing functions offered by an array DBMS provide effective analysis support.

DOI： 10.20965/jdr.2018.p0338

Sequenced Route Query with Semantic Hierarchy Reviewed

Yuya Sasaki, Yoshiharu Ishikawa, Yasuhiro Fujiwara, Makoto Onizuka

Proceedings of 21st International Conference on Extending Database Technology (EDBT 2018) page： 37-48 2018.3

GPH: Similarity Search in Hamming Space

Jianbin Qin, Yaoshu Wang, Chuan Xiao, Wei Wang, Xuemin Lin, Yoshiharu Ishikawa

Proceedings of 34th International Conference on Data Engineering (ICDE 2018) page： (not fixed) 2018.4

CiNCT: Compression and Retrieval for Massive Vehicular Trajectories via Relative Movement Labeling Reviewed

Satoshi Koide, Yukihiro Tadokoro, Chuan Xiao, Yoshiharu Ishikawa

Proceedings of 34th International Conference on Data Engineering (ICDE 2018) page： (not fixed) 2018.4

Histogram Construction for Difference Analysis of Spatio-Temporal Data on Array DBMS Reviewed

Jing Zhao, Yoshiharu Ishikawa, Chuan Xiao, Kento Sugiura

2018 Australasian Database Conference (ADC 2018) page： 41-52 2018.5

Language：English

To analyze scientific data, there are frequent demands for comparing multiple datasets on the same subject to detect any differences between them. For instance, comparison of observation datasets in a certain spatial area at different times or comparison of spatial simulation datasets with different parameters are considered to be important. Therefore, this paper proposes a difference operator in spatio-temporal data warehouses, based on the notion of histograms in the database research area. We propose a difference histogram construction method and they are used for effective and efficient data visualization in difference analysis. In addition, we implement the proposed algorithms on an array DBMSs SciDB, which is appropriate to process and manage scientific data. Experiments are conducted using mass evacuation simulation data in tsunami disasters, and the effectiveness and efficiency of our methods are verified.

DOI： 10.1007/978-3-319-92013-9_4

地域のサステナビリティとレジリエンスを同時に考慮できる評価システムの開発

朴秀日, 加藤博和, 石川佳治, 山中英生, 奥嶋政嗣, 渡辺公次郎

第57回土木計画学研究発表会・講演集 page： 36-01 2018.6

Enhanced Indexing and Querying of Trajectories in Road Networks via String Algorithms Reviewed

Satoshi Koide, Yukihiro Tadokoro, Takayoshi Yoshimura, Chuan Xiao, Yoshiharu Ishikawa

ACM Transactions on Spatial Algorithms and Systems Vol. 4 ( 1 ) page： 3 2018.6

Language：English Publishing type：Research paper (scientific journal)

In this article, we propose a novel indexing and querying method for trajectories constrained in a road network. We aim to provide efficient algorithms for various types of spatiotemporal queries that involve routing in road networks, such as (1) finding moving objects that have traveled along a given path during a given time interval, (2) extracting all paths traveled after a given spatiotemporal context, and (3) enumerating all paths between two locations traveled during a certain time interval. Unlike the existing methods in spatial database research, we employ indexing techniques and algorithms from string processing. This idea is based on the fact that we can represent spatial paths as strings, because trajectories in a network are represented as sequences of road segment IDs. The proposed SNT-index (suffix-array-based network-constrained trajectory index) introduces two novel concepts to trajectory indexing. The first is FM-index, which is a compact in-memory data structure for pattern matching. The second is an inverse suffix array, which allows the FM-index to be integrated with the temporal information stored in a forest of B+-trees. Thanks to these concepts, we can reduce the number of B+-tree accesses required by the query processing algorithms to a constant number, something that cannot be achieved with existing methods. Although an FM-index is essentially a static index, we also propose a practical method of appending new data to the index. Finally, experiments show that our method can process the target queries for more than 1 million trajectories in a few tens of milliseconds, which is significantly faster than what the baseline algorithms can achieve without string algorithms.

DOI： 10.1145/3200200

Top-k Query Processing with Replication Strategy in Mobile Ad Hoc Networks Reviewed

Yuya Sasaki, Takahiro Hara, Shojiro Nishio, Yoshiharu Ishikawa

19th IEEE International Conference on Mobile Data Management (MDM 2018) page： 217-226 2018.6

Language：English

In this paper, we propose a method that fully combines top-k query processing with replication strategy in mobile ad hoc networks (MANETs). The goal is to acquire perfect accuracy of query results with a minimal overhead and delay. Currently, no replication strategy achieves efficient allocation of replicas for top-k queries, and no top-k query processing guarantees perfect accuracy of query results in MANETs. We propose a new replication strategy FReT (topology-Free Replication for Top-k query) and new top-k query processing methods. FReT advantages efficient top-k query processing from limited search area even if mobile nodes move. In our top-k query processing method, the search area gradually increases until receiving an exact answer. We demonstrate, through extensive simulations, that our approaches function well in terms of small delay and overhead.

DOI： 10.1109/MDM.2018.00039

ユーザの位置情報を考慮した領域内の影響最大化に対する効率的なアプローチ

勝田健斗, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-003 2018.9

テンソル分解を用いた避難移動軌跡データの分析

河井悠佑, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-004 2018.9

データストリームの集約処理における近似的耐障害性に関する一考察

高尾大樹, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-017 2018.9

気候変動に対応した地域のサステナビリティとレジリエンスを同時に考慮できる評価手法

朴秀日, 加藤博和, 清水大夢, 大野悠貴, 石川佳治, 山中英生, 奥嶋政嗣, 渡辺公次郎, 井若和久, 秋山祐樹

58回土木計画学研究発表会・秋大会論文集 page：（頁番号なし） 2018.11

Loquat: An Interactive System Design for Location-aware Query Autocompletion Reviewed

Sheng Hu, Chuan Xiao, Yoshiharu Ishikawa

9th International Conference on Networking and Information Technology (ICNIT 2018) page： no-page 2018.11

Simulation Data Summarization based on Spatial Histograms Reviewed

Jing Zhao, Yoshiharu Ishikawa, Chuan Xiao, Kento Sugiura

Proceedings of the 21st International Conference on Network and Computing Technology (ICNCT 2019) page： (no page info) 2019.1

Regular Expression Pattern Matching with Sliding Windows over Probabilistic Event Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa

The 6th IEEE International Conference on Big Data and Smart Computing (IEEE BigComp 2019) 2019.2

Language：English

As smartphones and IoT devices become widespread, event streams, which are continuous analysis results of sensing data, have received a Iot of attention. When we consider the utilization of event streams, it is important to deal with probabilistic event streams due to the noises of sensing data and the limitation of analysis techniques. Although existing methods proposed the monitoring of time series events with regular expressions, there is no efficient method to calculate the occurrence probabilities of time series events with a sliding window. That is, existing methods cannot answer a query such as “does the specified time series event occur in last w time steps?” efficiently. Thus, in this paper, we propose an efficient calculation method by using a deterministic finite automaton (DFA). To calculate occurrence probabilities efficiently, our method divide a window into chunks and reuse the previous calculation results. Besides, we apply lazy evaluation to solve the state explosion problem of a DFA. Experimental results using real and synthetic datasets demonstrate effectiveness and efficiency of our approach.

DOI： 10.1109/BIGCOMP.2019.8679461

Road Segment Interpolation for Incomplete Road Data Reviewed

Yuya Sasaki, Jiahao Yu, Yoshiharu Ishikawa

The 6th IEEE International Conference on Big Data and Smart Computing (IEEE BigComp 2019) page： 10.1109/BIGCOMP.2019.8679461 2019.2

Language：English

Road data is fundamental information for location-based services. We trust that the road data is complete to represent an actual road network when we develop the location-based services. However, road data may be incomplete due to update delays, and thus location-based services may not provide useful results. Several algorithms have been proposed to automatically update road data. In this paper, we study interpolation of missing road segments by using vehicle trajectory data. We can find missing road segments from the trajectories because vehicles may pass through road segments that are not included in road data. However, trajectories are inherently noisy due to GPS errors. Hence, we cannot easily interpolate appropriate road segments. We propose an algorithm based on map matching and clustering techniques for achieving accurate and comprehensive interpolation. Our algorithm first detects trajectories that are probably on missing road segments. It then clusters the trajectories by DBSCAN and integrates the trajectories for interpolating the road data. Through the experiments using real incomplete road data and trajectory data, we verify that our algorithm effectively interpolates the missing road segments.

Estimating People Flow from a Large Amount of Aggregated Data with a Few Tracking Data Reviewed

Yusuke Kawai, Yusuke Tanaka, Hiroyuki Toda, Yoshiharu Ishikawa

DBSJ Japanese Journal Vol. 17 page： Article No. 7 2019.3

ソーシャルネットワークにおける特定のユーザを対象とした影響最大化

勝田健斗, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D2-2 2019.3

識別モデルを用いたスコープを意識したコード補完 Reviewed

胡晟, 肖川, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： G4-1 2019.3

確率モデルに基づく近似的な耐障害性の保証

高尾大樹, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D4-3 2019.3

データストリーム管理システムに関する再考

杉浦健人, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D4-4 2019.3

テンソル分解を用いた避難移動軌跡データの分析

河井悠佑, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： A6-2 2019.3

道路ネットワークのスパース性に着目した車両軌跡の圧縮索引

小出智士, 肖川, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D7-4 2019.3

データベース管理システムにおける3D TIN 管理の検討

杉浦健人, 椎名健, 石川佳治

第81回情報処理学会全国大会 page： 2C-3 2019.3

大規模点群データ分析のためのデータベースの検討

笠井雄太, 石川佳治, 杉浦健人

第81回情報処理学会全国大会 page： 2Q-5 2019.3

Indexing Trajectories for Travel-Time Histogram Retrieval Reviewed

Robert Waury, Christian S. Jensen, Satoshi Koide, Yoshiharu Ishikawa, Chuan Xiao

22nd International Conference on Extending Database Technology (EDBT 2019) page： 157-168 2019.3

Analysis of Evacuation Trajectory Data Using Tensor Decomposition Reviewed

Yusuke Kawai, Yoshiharu Ishikawa, Kento Sugiura

Journal of Disaster Research Vol. 14 ( 3 ) page： 521-530 2019.3

Hierarchical Histograms for Exploratory Analysis of Spatio-Temporal Array Data Reviewed

Jing Zhao, Yoshiharu Ishikawa, Lei Chen, Chuan Xiao, Kento Sugiura

IEICE Transactions on Information and Systems Vol. E102-D ( 4 ) page： 788-799 2019.4

Autocompletion for Prefix-Abbreviated Input Reviewed

Sheng Hu, Chuan Xiao, Jianbin Qin, Yoshiharu Ishikawa, Qiang Ma

ACM SIGMOD International Conference on Management of Data (SIGMOD 2019) page： 211-228 2019.6

Language：English

Query autocompletion (QAC) is an important interactive feature that assists users in formulating queries and saving keystrokes. Due to the convenience it brings to users, QAC has been adopted in many applications, including Web search engines, integrated development environments (IDEs), and mobile devices. For existing QAC methods, users have to manually type delimiters to separate keywords in their inputs. In this paper, we propose a novel QAC paradigm through which users may abbreviate keywords by prefixes and do not have to explicitly separate them. Such paradigm is useful for applications where it is inconvenient to specify delimiters, such as desktop search, text editors, and input method editors. E.g., in an IDE, users may input getnev and we suggest GetNextValue. We show that the query processing method for traditional QAC, which utilizes a trie index, is inefficient under the new problem setting. A novel indexing and query processing scheme is hence proposed to efficiently complete queries. To suggest meaningful results, we devise a ranking method based on a Gaussian mixture model, taking into consideration the way in which users abbreviate keywords, as opposed to the traditional ranking method that merely considers popularity. Efficient top-k query processing techniques are developed on top of the new index structure. Experiments demonstrate the effectiveness of the new QAC paradigm and the efficiency of the proposed query processing method.

DOI： 10.1145/3299869.3319858

Scope-aware Code Completion with Discriminative Modeling Reviewed

Sheng Hu, Chuan Xiao, Yoshiharu Ishikawa

Journal of Information Processing (JIP) Vol. 27 page： 469-478 2019.8

Language：English Publishing type：Research paper (scientific journal)

Code completion is a traditional popular feature for API access in integrated development environments (IDEs). It not only frees programmers from remembering specific details about an API but also saves keystrokes and corrects typographical errors. Existing methods for code completion usually suggest APIs based on statistics in code bases described by language models. However, they neglect the fact that the user's input is also very useful for ranking, as the underlying patterns can be used to improve the accuracy of predictions of intended APIs. In this paper, we propose a novel method to improve the quality of code completion by incorporating the users' acronym-like input conventions and the APIs' scope context into a discriminative model. The users' input conventions are learned using a logistic regression model by extracting features from collected training data. The weights in the discriminative model are learned using a support vector machine (SVM). To improve the real-time efficiency of code completion, we employ a trie to index and store the scope context information. An efficient top-k algorithm is developed. Experiments show that our proposed method outperforms the baseline methods in terms of both effectiveness and efficiency.

DOI： 10.2197/ipsjjip.27.469

多次元データ分析のための可視化推薦システム

野田昌太郎, 杉浦健人, 石川佳治

第18回情報技術フォーラム（FIT 2019） page： D-002 2019.9

データベースのスキーマ情報を活用した機械学習

志村薫, 杉浦健人, 石川佳治

第18回情報技術フォーラム（FIT 2019） page： D-008 2019.9

略語のフルネームのスケーラブルな推測

高明敏, 肖川, 石川佳治

第18回情報技術フォーラム（FIT 2019） page： D-009 2019.9

センサストリーム処理のための近似的耐障害性保証

高尾大樹, 石川佳治, 杉浦健人

情報処理学会研究報告 Vol. 2019-DBS-169 ( 12 ) page： (no page no.) 2019.9

Efficient Framework for Processing Top-k Queries with Replication in Mobile Ad Hoc Networks Reviewed

Yuya Sasaki, Takahiro Hara, Yoshiharu Ishikawa

GeoInformatica Vol. 23 ( 4 ) page： 591-620 2019.10

Language：English Publishing type：Research paper (scientific journal)

This article addresses the top-k query processing problem on mobile ad hoc networks (MANETs). Top-k query processing is common to retrieve only highly important data items. However, methods for top-k query processing are not enough efficient and accurate in MANET environments. For improving the efficiency and accuracy, replication is a promising technique that each node in MANETs replicates data items retained by other nodes into its storage. Therefore, we fully combine the top-k query processing with data replication. We propose a framework that efficiently processes top-k queries based on a new replication strategy. We develop new replication strategy FReT (topology-Free Replication for Top-k query). FReT determines near-optimal allocations of replicas. It advantages efficient top-k query processing from limited search area without maintenance costs even if mobile nodes move. Our top-k query processing methods retrieve the exact answer with small overhead and delay by gradually increasing the search area based on FReT. We demonstrate, through extensive experiments, that FReT and query processing methods function well in terms of small delay and overhead without sacrificing exactness of the query result.

DOI： 10.1007/s10707-019-00363-0

Approximate Fault Tolerance for Sensor Stream Processing Reviewed

Daiki Takao, Kento Sugiura, Yoshiharu Ishikawa

Proceedings of the 31st Australasian Database Conference (ADC 2020) page： -- 2020.1

トライ木及びGMMに基づく略語のフルネームのスケーラブルな推測手法

高明敏, 肖川, 石川佳治

第12回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2020) 2020.3

チェックポインティングを考慮した近似的耐障害性保証

高尾大樹, 杉浦健人, 石川佳治

第12回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2020) page： H3-4 2020.3

並列ストリーム処理システムにおけるDBを用いた内部状態の共有手法

杉浦健人, 石川佳治

第12回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2020) page： I8-1 2020.3

多次元データの探索分析のための多様性を考慮した可視化システム

野田昌太郎, 杉浦健人, 石川佳治

第12回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2020) page： A8-3 2020.3

データベースのスキーマ情報を活用した機械学習

志村薫, 杉浦健人, 石川佳治

第12回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2020) page： D8-5 2020.3

メニーコアシステムにおける分散ストリーム処理システムの性能評価 - スループットに関する評価 -

德増直紀, 杉浦健人, 石川佳治

情報処理学会第82回全国大会 page： 7M-01 2020.3

メニーコアシステムにおける分散ストリーム処理システムの性能評価 - 遅延に関する評価 -

牧田直樹, 杉浦健人, 石川佳治

情報処理学会第82回全国大会 page： 7M-02 2020.3

RDBMSによる3D TINデータベース実装手法

田中玲史, 杉浦健人, 石川佳治

情報処理学会第82回全国大会 page： 5N-01 2020.3

Compressed Indexing for Trajectories Constrained in Road Networks Reviewed

Satoshi Koide, Chuan Xiao, Yoshiharu Ishikawa

Vol. J103-D ( 5 ) page： 393 - 402 2020.5

Multiple Regular Expression Pattern Monitoring over Probabilistic Event Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E103-D ( 5 ) page： 982 - 991 2020.5

Fast Subtrajectory Similarity Search in Road Networks under Weighted Edit Distance Constraints Reviewed

Satoshi Koide, Chuan Xiao, Yoshiharu Ishikawa

Proceedings of the VLDB Endowment (PVLDB) Vol. 13 ( 11 ) page： 2188 - 2201 2020.7

Efficient Query Autocompletion with Edit Distance-based Error Tolerance Reviewed International coauthorship

Jianbin Qin, Chuan Xiao, Sheng Hu, Jie Zhang, Wei Wang, Yoshiharu Ishikawa, Koji Tsuda, Kunihiko Sadakane

The VLDB Journal Vol. 29 ( 4 ) page： 919 - 943 2020.7

NGNC: A Flexible and Efficient Framework for Error-Tolerant Query Autocompletion Reviewed

Yukai Miao, Jianbin Qin, Sheng Hu, Yuyang Dong, Yoshiharu Ishikawa, Makoto Onizuka

Fourth Workshop on Software Foundations for Data Interoperability (SFDI 2020) page： 101-115 2020.9

機械学習を用いた近似的問合せ処理

倪天嘉, 石川佳治, 杉浦健人

第19回情報科学技術フォーラム (FIT 2020) page： D-002 2020.9

3次元TINデータ上での空間的スカイライン問合せ

笠井雄太, 杉浦健人, 石川佳治

第19回情報科学技術フォーラム (FIT 2020) page： D-003 2020.9

Rethinking the Local Similarity in Content-based Image Retrieval

Longjiao Zhao, Yu Wang, Yoshiharu Ishikawa, Jien Kato

電子情報通信学会パターン認識・メディア理解研究会 2020.12

Generalizing the Pigeonhole Principle for Similarity Search in Hamming Space Reviewed International coauthorship

Qin J., Xiao C., Wang Y., Wang W., Lin X., Ishikawa Y., Wang G.

IEEE Transactions on Knowledge and Data Engineering Vol. 33 ( 2 ) page： 489 - 505 2021.2

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEE Transactions on Knowledge and Data Engineering

A distance search in Hamming space finds binary vectors whose Hamming distances are no more than a threshold from a query vector. It is a fundamental problem in many applications, such as image retrieval, near-duplicate Web page detection, and scientific databases. State-of-the-art approaches to Hamming distance search are mainly based on the pigeonhole principle to generate a set of candidates and then verify them. We observe that the constraint by the pigeonhole principle is not always tight and may bring about unnecessary candidates. We also observe that the distribution in real data is often skewed, but most existing solutions adopt a simple equi-width partitioning and allocate the same threshold to all the parts, hence failing to exploit the data skewness to optimize query processing. In this paper, we propose a new form of the pigeonhole principle which allows variable partitioning and threshold allocation. Based on the new principle, we develop a tight constraint of candidates and devise cost-aware methods for partitioning and threshold allocation to optimize query processing. In addition, we extend our methods to answer Hamming distance join queries. We also discuss the application of the pigeonhole principle in set similarity search, a problem that can be converted to Hamming distance search equivalently. Our evaluation on datasets with various data distributions shows the robustness of our solution and its superior query processing performance to the state-of-the-art methods.

DOI： 10.1109/TKDE.2019.2899597

Scopus

誤差を保証する近似的問合せについて

倪天嘉, 杉浦健人, 石川佳治

第13回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2021) page： B11-2 2021.3

TIN上での空間的スカイライン問合せ

笠井雄太, 杉浦健人, 石川佳治

第13回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2021) page： A21-4 2021.3

エッジコンピューティング環境における低遅延かつ高可用な耐障害性保証

高尾大樹, 杉浦健人, 石川佳治

第13回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2021) page： J24-4 2021.3

マルチバージョン索引構造P-Treeの性能評価

野原健汰, 杉浦健人, 石川佳治

情報処理学会第83回全国大会 page： 5L-04 2021.3

不揮発性メモリのための索引手法の分析

西村学, 杉浦健人, 石川佳治

情報処理学会第83回全国大会 page： 5L-06 2021.3

機械学習による空間索引の性能評価

鈴木駿也, 杉浦健人, 石川佳治

情報処理学会第83回全国大会 page： 5L-08 2021.3

都市のサステナビリティ及びレジリエンス分析のためのインタフェースの開発

山本孝生, 石川佳治, 杉浦健人, 朴秀日, 加藤博和

情報処理学会第83回全国大会 page： 6L-07 2021.3

Approximate Streaming Aggregation with Low-Latency and High-Reliability for Edge Computing Reviewed

TAKAO Daiki, SUGIURA Kento, ISHIKAWA Yoshiharu

Vol. J104-D ( 5 ) page： 463 - 475 2021.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Edge computing enables communication traffic reduction and load balancing by simple data processing like aggregation or filtering at network edges. Low latency, high reliability, and fault tolerance are important requirements for edge computing applications. In this paper, we assume applications for environmental sensing and propose an approximate streaming aggregation algorithm that meets these requirements. Our method provides the result with theoretical error bounds, even if there are missing data due to sensor failures or communication failures. Furthermore, our method reduces latency by outputting the result when meeting user requirements and guarantees fault tolerance approximately by estimating the lost state.

DOI： 10.14923/transinfj.2020dep0004

CiNii Research

Consistent and Flexible Selectivity Estimation for High-Dimensional Data Reviewed International coauthorship

Yaoshu Wang, Chuan Xiao, Jianbin Qin, Rui Mao, Makoto Onizuka, Wei Wang, Rui Zhang, Yoshiharu Ishikawa

Proceedings of ACM SIGMOD International Conference on Management of Data (SIGMOD 2021) page： 2319 - 2327 2021.6

Spatial Skyline Queries on Triangulated Irregular Networks Reviewed

Kasai Y., Sugiura K., Ishikawa Y.

ACM International Conference Proceeding Series page： 64 - 73 2021.8

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ACM International Conference Proceeding Series

A spatial skyline query is a query to find a set of data points that are not spatially dominated by other data points, given a set of data points P and query points Q in a multidimensional space. The query enumerates the skyline points based on distance in a multidimensional space. However, existing spatial skyline queries can lead to large errors with actual travel distances in geo-spaces because the query is based on the Euclidean distance. We propose a spatial skyline query on triangulated irregular networks (TINs), which are frequently used to represent the surfaces of terrain. We define a new spatial skyline query based on more accurate travel distances considering the TIN distance instead of the Euclidean distance. We also propose an efficient solution method using indexes to find nearest-neighbor points in TIN space and reduce the numbers of unnecessary data points and TIN vertices. The proposed method achieves a computational complexity of O(|P′||Q|N′2 + |P′|2|Q|), where P′ and N′ are the reduced sets of data points and number of TIN vertices, respectively, based on the range of query points. The proposed method can process a query faster than the naive method with T(|P||Q|N2 + |P|2|Q|), where N is the number of TIN vertices. Moreover, experiments verify that the proposed method is faster than the naive method by using a spatial index to reduce the numbers of unnecessary data points and TIN vertices.

DOI： 10.1145/3469830.3470901

Scopus

エッジコンピューティングにおける時間的相関を考慮した近似的耐障害性保証

高尾大樹, 杉浦健人, 石川佳治, 陸可鏡

第20回情報科学技術フォーラム (FIT 2021) 2021.8

IoT環境におけるデータベースを用いた点群管理の検討

松本佳大, 杉浦健人, 石川佳治, 陸可鏡

第20回情報科学技術フォーラム (FIT 2021) 2021.8

誤差の保証がある近似的問合せ処理に関する研究

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

第20回情報科学技術フォーラム (FIT 2021) 2021.8

ロックフリー索引のための基礎ベンチマークの作成及び性能検証

牧田直樹, 杉浦健人, 石川佳治, 陸可鏡

第20回情報科学技術フォーラム (FIT 2021) 2021.8

並列データストリーム処理システムにおける内部状態共有手法の検討

徳増直紀, 杉浦健人, 石川佳治, 陸可鏡

第20回情報科学技術フォーラム (FIT 2021) 2021.8

Development of IPSJ Data Science Curriculum Standard Reviewed

Tetsuro Kakeshita, Kazuo Ishii, Yoshiharu Ishikawa, Hitoshi Matsubara, Yutaka Matsuo, Tsuyoshi Murata, Miyuki Nakano, Takako Nakatani, Haruhiko Okumura, Naoko Takahashi, Norimitsu Takahashi, Gyo Uchida, Eriko Uematsu, Satoshi Saeki and Hiroshi Kato

Proc. of Open Conference on Computers in Education (OCCE 2021 DTEL) 2021.8

Approximate Fault Tolerance for Edge Stream Processing Reviewed

Daiki Takao, Kento Sugiura, Yoshiharu Ishikawa

Proceedings of DEXA 2021 Workshops (ProTime 2021) Vol. 1479 CCIS page： 173 - 183 2021.9

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Communications in Computer and Information Science

Existing distributed stream processing systems generally guarantee fault tolerance by switching to standby machines and reprocessing lost data. In edge computing environments, however, we have to duplicate each edge for this conventional approach. This duplication cost increases sharply with expansion in the system scale. To solve this problem, we propose an approach to support approximate fault tolerance without edge duplication. We focus on environmental monitoring applications and utilize the correlation between sensors. In this paper, we assume that each edge estimates missing data from the observed data and aggregates them approximately. We provide a method to estimate the outputs of failed edges taking care of the uncertainty of the processing results at each edge. Our method allows the server to continue processing without waiting for the recovery of failed edges. We also show that the validity of our method by experiments using synthetic data.

DOI： 10.1007/978-3-030-87101-7_17

Scopus

HVS: Hierarchical Graph Structure Based on Voronoi Diagrams for Solving Approximate Nearest Neighbor Search Reviewed

Kejing Lu, Yoshiharu Ishikawa, Mineichi Kudo, Chuan Xiao

Proceedings of the VLDB Endowment (PVLDB) Vol. 15 ( 2 ) page： 246 - 258 2021.10

航空オブリーク撮影データからの3Dモデル高速作成の課題とその利活用

藤原紘子, 四俣徹, 杉浦健人, 石川佳治, 神林飛志, 埋金進一, 川口章, 佐藤俊明

第30回地理情報システム学会講演論文集 2021.10

航空機オブリーク画像からの3Dモデル作成の分散並列処理による高速化

四俣徹, 藤原紘子, 佐藤俊明, 大辻典, 杉浦健人, 石川佳治, 神林飛志, 埋金進一, 川口章, 鈴鹿守俊

日本写真測量学会秋季学術講演会発表論文集 2021.10

道路ネットワーク上の軌跡データに対する圧縮索引 Invited

小出智士, 肖川, 石川佳治

情報・システムソサイエティ誌 Vol. 26 ( 3 ) page： 10 - 10 2021.11

Approximate Fault-Tolerant Data Stream Aggregation for Edge Computing Invited

Takao D., Sugiura K., Ishikawa Y.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Vol. 13167 LNCS page： 233 - 244 2022

Language：Japanese Publishing type：Research paper (international conference proceedings) Publisher：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

With the development of IoT, edge computing has been attracting attention in recent years. In edge computing, simple data processing, such as aggregation and filtering, can be performed at network edges to reduce the amount of data communication and distribute the processing load. In edge computing applications, it is important to guarantee low latency, high reliability, and fault tolerance. We are working on the solution of this problem in the context of environmental sensing applications. In this paper, we outline our approach. In the proposed method, the aggregate value of each device is calculated approximately and the fault tolerance is also guaranteed approximately even when the input data is missing due to sensor device failure or communication failure. In addition, the proposed method reduces the delay by outputting the processing result when the error guarantee satisfies the user’s requirement.

DOI： 10.1007/978-3-030-96600-3_17

Scopus

Approximate Query Processing with Error Guarantees Reviewed

Tianjia Ni, Kento Sugiura, Yoshiharu Ishikawa, Kejing Lu

Ninth International Conference on Big Data Analytics in Astronomy, Science and Engineering (BDA 2021) Vol. 13167 LNCS page： 268 - 278 2021.12

In recent years, with the increase of data and the sophistication of analysis requirements, query processing in databases has become more important. Recently, approximate query processing (AQP) was proposed for efficiently executing database queries on big data. In this research, we focus on synopsis construction on a relational database and the query technology based on it, which is called Bounded Approximate Query (BAQ) proposed in 2019. BAQ is a synopsis construction method that focuses on aggregate queries using SQL, and realizes error-guaranteed query processing by grouping the dataset into the synopsis. In this paper, we point out the limitations of queries and datasets in BAQ and based on the result of experiments, we prove that the proposed method can be applied efficiently to data wider than the original BAQ with smaller synopsis within the error guarantee.

DOI： 10.1007/978-3-030-96600-3_20

Scopus

シノプシスに基づく近似問合せ処理における誤差保証の検討

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会研究報告データベースシステム（DBS） Vol. 2021-DBS-174(2) page： 1 - 6 2021.12

並列データストリーム処理におけるデータベースを用いた内部状態の共有

徳増直紀, 杉浦健人, 石川佳治, 陸可鏡

第14回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2022) 2022.2

シノプシスの最適化に基づく近似問合せ処理の高速化

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

第14回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2022) 2022.2

近似的な耐障害性保証に基づくエッジストリーム処理システムの開発

高尾大樹, 杉浦健人, 石川佳治, 陸可鏡

第14回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2022) 2022.2

ロックフリー索引構造Bw木の再現実装及び性能評価

牧田直樹, 杉浦健人, 石川佳治, 陸可鏡

第14回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2022) 2022.2

動的点群のデータベースを用いた管理手法

松本佳大, 杉浦健人, 石川佳治, 陸可鏡

第14回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2022) 2022.2

Bw木およびBz木における範囲走査性能の評価

平野匠真，杉浦健人，石川佳治，陸可鏡

情報処理学会第84回全国大会 2022.3

ロックフリー索引BzTreeにおける並列一括挿入法の実装

中山宗，杉浦健人，石川佳治，陸可鏡

情報処理学会第84回全国大会 2022.3

Implementation of a Multi-Word Compare-and-Swap Operation without Garbage Collection Reviewed

Kento Sugiura, Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E105-D ( 5 ) page： 946 - 954 2022.5

B⁺木における同時実行制御手法の性能検証

野原健汰, 杉浦健人, 石川佳治

情報処理学会研究報告データベースシステム (DBS) Vol. 2022-DBS-175 2022.9

永続メモリ向けMulti-Word Compare-and-Swap命令の改善

西村学, 杉浦健人, 石川佳治

情報処理学会研究報告データベースシステム (DBS) Vol. 2022-DBS-175 2022.9

近似的問合せ処理における問合せ高速化のための誤差保証条件の検討

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会研究報告データベースシステム (DBS) Vol. 2022-DBS-175 2022.9

機械学習を用いた検索エッジ数の推定によるグラフベース近似最近傍探索の高速化

菅寧, 陸可鏡, 石川佳治, 杉浦健人

第21回情報科学技術フォーラム (FIT 2022) 2022.9

航空オブリーク画像からの広域3DTin高速作成システム構築と災害時実証実験について

藤原紘子, 大辻喜典, 杉浦健人, 石川佳治, 神林飛志, 埋金進一, 川口章, 薮下雄平, 鈴鹿守俊, 佐藤俊明

地理情報システム学会第31回学術研究発表大会 2022.10

MQH: Locality Sensitive Hashing on Multi-level Quantization Errors for Point-to-Hyperplane Distances Reviewed

Kejing Lu, Yoshiharu Ishikawa, Chuan Xiao

Proceedings of the VLDB Endowment (PVLDB) Vol. 16 ( 4 ) page： 864 - 876 2023.1

B⁺木のマルチバージョン化による範囲走査性能への影響評価

桑村真生, 杉浦健人, 野原健汰, 石川佳治, 陸可鏡

情報処理学会第85回全国大会講演論文集 2023.3

Bz木における範囲走査性能の改善

井戸佑, 杉浦健人, 中山宗, 石川佳治, 陸可鏡

情報処理学会第85回全国大会講演論文集 2023.3

Bz木におけるマルチスレッドでの構造変更操作に関する性能評価

中山宗, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第85回全国大会講演論文集 2023.3

Bw木におけるマルチスレッドでの構造変更操作に関する性能評価

平野匠真, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第85回全国大会講演論文集 2023.3

誤差上限付き近似問合せ処理におけるシノプシス構築の高速化

堀崎祥, 倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第85回全国大会講演論文集 2023.3

近似的問合せ処理におけるシノプシス構築の高速化

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.2

B⁺木における同時実行制御手法の統一的な再現実装及び性能検証

野原健汰, 鈴木駿也, 杉浦健人, 石川佳治, 陸可鏡

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.3

Adaptive Radix Treeの多次元索引への拡張

鈴木駿也, 杉浦健人, 石川佳治, 陸可鏡

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.3

機械学習によるグラフベース近似最近傍探索の高速化

菅寧, 陸可鏡, 杉浦健人, 石川佳治

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.3

永続メモリ向けMulti-Word Compare-and-Swap命令の改善

西村学, 杉浦健人, 石川佳治

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.3

エッジコンピューティング環境を想定した近似的な耐障害性保証に基づくデータストリーム処理システム

高尾大樹, 杉浦健人, 石川佳治, 陸可鏡

第15回データ工学と情報マネジメントに関するフォーラム（DEIM 2023) 2023.3

Learning Local Similarity with Spatial Interrelations on Content-Based Image Retrieval Open Access

ZHAO Longjiao, WANG Yu, KATO Jien, ISHIKAWA Yoshiharu

IEICE Transactions on Information and Systems Vol. E106.D ( 5 ) page： 1069 - 1080 2023.5

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Convolutional Neural Networks (CNNs) have recently demonstrated outstanding performance in image retrieval tasks. Local convolutional features extracted by CNNs, in particular, show exceptional capability in discrimination. Recent research in this field has concentrated on pooling methods that incorporate local features into global features and assess the global similarity of two images. However, the pooling methods sacrifice the image's local region information and spatial relationships, which are precisely known as the keys to the robustness against occlusion and viewpoint changes. In this paper, instead of pooling methods, we propose an alternative method based on local similarity, determined by directly using local convolutional features. Specifically, we first define three forms of local similarity tensors (LSTs), which take into account information about local regions as well as spatial relationships between them. We then construct a similarity CNN model (SCNN) based on LSTs to assess the similarity between the query and gallery images. The ideal configuration of our method is sought through thorough experiments from three perspectives: local region size, local region content, and spatial relationships between local regions. The experimental results on a modified open dataset (where query images are limited to occluded ones) confirm that the proposed method outperforms the pooling methods because of robustness enhancement. Furthermore, testing on three public retrieval datasets shows that combining LSTs with conventional pooling methods achieves the best results.

DOI： 10.1587/transinf.2022edp7163

Scopus

CiNii Research

永続メモリ向けロックフリー索引Bz木の改善

中山宗, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会研究報告 Vol. 2023-DBS-177 ( 38 ) page： 1 - 6 2023.9

同時実行B+木におけるロックフリー手続きの改善と実装

平野匠真, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会研究報告 Vol. Vol. 2023-DBS-177 ( 39 ) page： 1 - 6 2023.9

誤差保証付き近似的問合せ処理におけるシノプシス構築の高速化 Invited Reviewed

倪天嘉, 杉浦健人, 石川佳治, 陸可鏡

第16回データ工学と情報マネジメントに関するフォーラム（DEIM 2024） 2024.2

同時実行B⁺木におけるロックフリー手続きの改善と実装

平野匠真, 杉浦健人, 石川佳治, 陸可鏡

第16回データ工学と情報マネジメントに関するフォーラム（DEIM 2024） 2024.2

同時実行B⁺木のマルチバージョン化の検討

桑村真生, 杉浦健人, 平野匠真, 石川佳治, 陸可鏡

第16回データ工学と情報マネジメントに関するフォーラム（DEIM 2024） 2024.2

永続メモリ向けロックフリー索引Bz木に関する研究

中山宗, 杉浦健人, 石川佳治, 陸可鏡

第16回データ工学と情報マネジメントに関するフォーラム（DEIM 2024） 2024.2

来歴情報を活用したデータベースからの因果推論

大岩和樹, 石川佳治, 杉浦健人, 陸可鏡

第16回データ工学と情報マネジメントに関するフォーラム（DEIM 2024） 2024.2

因果推論に基づくデータベースからの仮説問合せについて

大岩和樹, 石川佳治, 杉浦健人, 陸可鏡

情報処理学会第86回全国大会 2024.2

確率的イベントストリームにおける最小記述長に基づく代表系列パターンの検出

中村航規, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第86回全国大会 2024.2

Universal Adaptive Radix Treeにおける空間分割戦略の改善

杉江祐介, 杉浦健人, 石川佳治, 陸可鏡, 井戸佑

情報処理学会第86回全国大会 2024.2

Watermark Management for Edge Computing System Based on Approximate Fault Tolerance Reviewed

TAKAO Daiki, SUGIURA Kento, ISHIKAWA Yoshiharu, LU Kejing

Vol. J107-D ( 5 ) page： 335 - 347 2024.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Data loss due to failure is an important issue in data stream processing for edge computing. In particular, the detection of data loss is a big problem, and the conventional method accumulates delays. In this paper, we propose a watermark management method based on the cooperation of edges and a gateway. Our method estimates lost data at a later stage and generates watermarks based on user's error requirements. We utilize an error guarantee mechanism to calculate the error requirements for edges in each failure situation. We show that our method can recover lost data precisely and reduce delays according to the user's requirements through experiments.

DOI： 10.14923/transinfj.2023dep0007

CiNii Research

Probabilistic Routing for Graph-Based Approximate Nearest Neighbor Search Reviewed

Kejing Lu, Chuan Xiao, Yoshiharu Ishikawa

Proceedings of Machine Learning Research Vol. 235 page： 33177 - 33195 2024.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Machine Learning Research

Approximate nearest neighbor search (ANNS) in high-dimensional spaces is a pivotal challenge in the field of machine learning. In recent years, graph-based methods have emerged as the superior approach to ANNS, establishing a new state of the art. Although various optimizations for graph-based ANNS have been introduced, they predominantly rely on heuristic methods that lack formal theoretical backing. This paper aims to enhance routing within graph-based ANNS by introducing a method that offers a probabilistic guarantee when exploring a node's neighbors in the graph. We formulate the problem as probabilistic routing and develop two baseline strategies by incorporating locality-sensitive techniques. Subsequently, we introduce PEOs, a novel approach that efficiently identifies which neighbors in the graph should be considered for exact distance calculation, thus significantly improving efficiency in practice. Our experiments demonstrate that equipping PEOs can increase throughput on commonly utilized graph indexes (HNSW and NSSG) by a factor of 1.6 to 2.5, and its efficiency consistently outperforms the leading-edge routing technique by 1.1 to 1.4 times. The code and datasets used for our evaluations are publicly accessible at https://github.com/ICML2024-code/PEOs.

Scopus

Acceleration of Synopsis Construction for Bounded Approximate Query Processing Reviewed

Tianjia Ni, Kento Sugiura, Yoshiharu Ishikawa, Kejing Lu

The DASFAA 2024 Workshop on Emerging Results in Data Science and Engineering (ERDSE 2024) Vol. 14667 LNCS page： 236 - 251 2025.1

データベースにおける仮説推論問合せについて

大岩和樹, 石川佳治, 杉浦健人, 陸可鏡

情報処理学会研究報告 Vol. 2024-DBS-179 2024.9

ロックフリー索引のトライ木化による高速化に関する研究

井戸佑, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会研究報告 Vol. 2024-DBS-179 2024.9

Guaranteeing an Exact Error Bound for Bounded Approximate Query Processing Reviewed

Tianjia Ni, Kento Sugiura, Yoshiharu Ishikawa, Kejing Lu

Journal of Information Processing Vol. 32 ( 0 ) page： 903 - 915 2024.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Information Processing Society of Japan

In recent years, efficient query processing in databases has become more crucial with the sophistication of analysis requirements. Approximate query processing (AQP) is one of the approaches to dealing with database queries on big data. In this research, we focus on synopsis construction on a relational database and the query technology based on it, called bounded approximate query processing (BAQ). This paper points out the limitations of existing research BAQ and solves them by the proposed BAQ±. BAQ± is capable of dealing datasets with a broader range while ensuring the exact error bound. Furthermore, compared to the original BAQ, BAQ± generates a more compact synopsis with various data distributions. We introduce an innovative bucketing approach to construct smaller synopses while keeping the same properties in BAQ. Additionally, we propose novel rewrite methods for answering online queries by deriving error guarantee conditions. We provide extensive experiment assessments using different distribution datasets. Our BAQ± provides a smaller synopsis at 64% the size of BAQ and efficiently executes online queries within the exact error bound.

DOI： 10.2197/ipsjjip.32.903

Scopus

CiNii Research

researchmap

Hierarchical and Efficient Synopsis Construction for Bounded Approximate Query Processing Reviewed Open Access

Tianjia Ni, Kento Sugiura, Yoshiharu Ishikawa, Kejing Lu

Journal of Information Processing Vol. 33 ( 0 ) page： 115 - 127 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Information Processing Society of Japan

Approximate query processing (AQP) has gained traction as an effective technique for executing queries on big data. Bounded approximate query processing (BAQ) is a recently proposed framework that stores a summary of an original table as a synopsis and ensures that its approximation errors remain below a user-specified threshold. Based on the BAQ framework, we have extended it to BAQ± to guarantee strictly bounded errors for more diverse data. However, BAQ and BAQ± still have problems when constructing synopses. They require time-consuming data sorting for each numerical attribute and cannot summarize high-cardinality categorical attributes, such as spatiotemporal data. To overcome these problems, we propose a novel framework called Hierarchical BAQ (HBAQ) and a synopsis construction method in this paper. HBAQ constructs multiple synopses based on the dimension tables of several categorical attributes and uses them to answer OLAP queries efficiently. We also introduce a new bucket definition to summarize numerical attributes effectively and support incremental updates for synopses. We conducted extensive experiments with several datasets. The experimental results show that HBAQ achieved half the construction time of BAQ with lower memory consumption. Furthermore, HBAQ could answer OLAP queries more efficiently than BAQ using hierarchically constructed synopses.

DOI： 10.2197/ipsjjip.33.115

Open Access

Scopus

CiNii Research

データベースにおける来歴情報を考慮した仮説推論問合せのための問合せ言語とその実装

大岩和樹, 石川佳治, 杉浦健人, 陸可鏡

第17回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2025) 2025.2

同時実行B+木のマルチバージョン化と範囲走査性能の評価

桑村真生, 杉浦健人, 石川佳治, 陸可鏡

第17回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2025) 2025.2

ロックフリー索引のトライ木化による改善と評価

井戸佑, 杉浦健人, 石川佳治, 陸可鏡

第17回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2025) 2025.2

部分ステートマシンレプリケーションにおける投機的分散トランザクション処理

白石裕輝、杉浦健人、石川佳治

第17回データ工学と情報マネジメントに関するフォーラム (DEIM Forum 2025) 2025.2

バックオフ戦略によるロックフリーMulti-Word Compare-and-Swap命令の改善

吽野元基, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第87回全国大会 2025.3

楽観的ロック手法OptiQLの再現実装及び性能評価

阿井星后, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第87回全国大会 2025.3

多腕バンディットを利用した自動索引作成の再現実装及び性能評価

張智嘉, 郭宏遠, 杉浦健人, 石川佳治, 陸可鏡

情報処理学会第87回全国大会 2025.3

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