Abstracts:

Yahiko Kambayashi, Akihiro Hatanaka, Akira Okada, Madoka Yuriyama
Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto-shi, Kyoto-fu, Japan    yahiko@isse.kuis.kyoto-u.ac.jp   hatanaka@isse.kuis.kyoto-u.ac.jp   aokada@isse.kuis.kyoto-u.ac.jp madoka@isse.kuis.kyoto-u.ac.jp

Action views and action history views are promising tool for CSCW (Computer Supported Cooperative Work) with security and privacy constraints. If we combine video with action history sequence, high-level functions for retrieving arbitrary portion of video data can be realized. How to use such functions for distance education is discussed in this paper. Four major topics are (1) recording functions for lecture, (2) retrieval functions for arbitrary portions of lecture video, (3) on-line quiz functions, and (4) discussion support for students.

Keywords: User Cooperation, CSCW, database view, video database, distance education

Yun Yang
School of Information Technology, Swinburne University of Technology, Hawthorn, Australia 3122    yun@it.swin.edu.au

Given the exposure of the Internet and the Web, there is a significant impact on Web-based cooperative teamwork support which can be beneficial to many teamwork managers and normal team members who may be either computing or non-computing professionals. In this paper, we focus on our research into a more effective architecture for Web-based teamwork automation support and its corresponding innovative mechanisms for various perspectives including visual process modelling for teamwork managers and process enactment for team members in an asynchronous and synchronous manner. Our research prototype is implemented in Java and the data repository used can be an object-oriented or relational database.

Keywords:teamwork, CSCW, processes, Java, Web, visualisation, databasesnt

Toyokazu Akiyama, Takahiro Hara, Kaname Harumoto, Masahiko Tsukamoto and Shojiro Nishio
Dept. of Information Systems Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan    akiyama@ise.eng.osaka-u.ac.jp hara@ise.eng.osaka-u.ac.jp harumoto@ise.eng.osaka-u.ac.jp tukao@ise.eng.osaka-u.ac.jp nishio@ise.eng.osaka-u.ac.jp

Due to the recent development of network technologies, broader channel bandwidth is becoming available everywhere in the world-wide networks. Based on this fact, we have proposed a new technology that makes good use of such broad bandwidth by dynamically relocating the databases through networks, which we call database migration. In the method proposed previously, it was assumed that we know the sequence of accesses to the system, this is used for database relocation. However, in order to use database migration in a practical environment, it is necessary to detect the access skew. In this paper, we propose a database relocation method which detects access skew from the access information. Moreover, we examine the effectiveness of the proposed method by comparing it with the conventional database-fixed method.

Keywords:DB-migration, distributed database management, transaction processing, access pattern

and
Eshed Xuemin Lin
School of Computer Sci. & Engineering, Uni. of New South Wales, Sydney NSW2052 Australia lxue@cse.unsw.edu.au  

OzGateway is a cooperative database system designed for integrating heterogeneous existing information systems into an interoperable environment. It also aims to provide a gateway for legacy information system migration. This paper summarises the problems and results of multidatabase transaction management research. In supporting globalupdates in OzGateway in an evolutionary way, we introduce a classification of multidatabase transactions and discuss the problems in each category. The architecture of OzGateway and the design of the global transaction manager and servers are presented.

Keywords:Multidatabases, Global Transaction Management, Transaction Classification

Tsuyoshi Takayama
Faculty of Software and Information Science, Iwate Prefectural University 152-52 Takizawa-aza-sugo, Takizawa, Iwate, 020-0173, Japan fujino@csys.ce.hiroshima-cu.ac.jp takayama@soft.iwate-pu.ac.jp

This paper proposes an approach to improving the performance of Thakore's algorithm with the speculative execution technique and dynamic task scheduling. Recently, object-oriented databases are being used in many applications, and are becoming larger and more complex. As a result, their response time is becoming longer. In order to reduce the response time, many parallel query processing approaches are proposed. The algorithm presented by Thakore et al. in 1995 is one of the representatives of such parallel approaches, but has a problem on load balancing. In order to reduce the problem, we modify this algorithm in two points: (i) introduce the speculative execution technique, and (ii) adopt dynamic task scheduling in assignment between a class and a processing node. These two modifications lead to a performance improvement of the original algorithm. Its effectiveness is shown with some evaluations.

Keywords:Object-oriented database, query processing, parallel processing, speculative execution, performance improvement, performance evaluation

Vladimir A. Fomichov
Faculty of Applied Mathematics, Moscow State Institute of Electronics and Mathematics - Technical University, 109028 Moscow, Russia and Department of Information Technologies K.E.Tsiolkovsky Russian State Technological University - "MATI" Orshanskaya 3, 121552 Moscow, Russia    vladfom@yahoo.com vaf@mech.math.msu.su

Formalizing conversation of intelligent agents (IAs) which realize Electronic Commerce (EC) includes such aspects as representing knowledge, goals, intentions, and actions of IAs, representing contents of messages (including arbitrary protocols of negotiations) and communicative acts. A common mathematical framework is suggested for all these purposes. This framework is the theory of restricted K-calculuses and K-languages (RKCL-theory), published by the author in Informatica, 1996, No. 1, 1998, No. 4. The suggested mathematical framework possesses all expressive possibilities of the Semantic Language published in 1999 in Geneva by the Foundation for Intelligent Physical Agents (FIPA SL) and of FIPA Agent Communication Language (FIPA ACL). Besides, this framework provides many advantages in comparison with FIPA SL. One of the principal advantages is that a collection of 10 rules is suggested such that one is able to construct the representations of the contents (or structured meanings) of arbitrary natural language discourses and, as a consequence, to construct the representations of arbitrarily complicated goals, actions, and negotiation protocols proceeding from elementary informational items and applying these rules. As a result, the RKCL-theory allows for building compound designations of arbitrary entities considered in the field of EC: sets, finite sequences, relationships, concepts, and structured meanings of texts. That is why the described framework is called an ontological framework. It is shown that the expressive power of restricted standard K-languages exceeds the expressive power of the Resource Description Framework (RDF) and RDF Schema Specification Language elaborated in 1998-1999 by the WWW-Consortium. It is suggested to use the RKCL-theory as a reference-point and a tool for developing more powerful and flexible conceptual formalisms for the advanced, semantically-structured Web

Keywords:multi-agent system; electronic commerce; content language; agent communication language; World Wide Web; semantically-structured Web; Resource Description Framework; semantic representation; conceptual formalism; universal conceptual metagrammar; integral formal semantics; restricted K-calculuses; restricted standard K-languages, FIPA Semantic Language

Tung-Shu Chen
Department of Computer Science and Information Management Providence University, Taichung, Taiwan 433, R.O.C.   tchen@pu.edu.tw

In this paper, a new watermarking method is proposed for copyright protection of two-color bitmaps. It is called the threshold watermarking method (TW). TW combines a watermark and a two-color bitmap together. This combination is basically achieved following the concept of the (t,n)-threshold scheme. TW extracts n characteristic values from the bitmap first and thus generates some information to protect the copyright of this bitmap. TW guarantees that it can fight against modificative attacks if there are more than t characteristic values existing in the modified bitmap. This phenomenon has been shown in our experiments. Hence TW is a robust watermarking method.

Keywords:(t,n )-threshold scheme, Torus automorphism, digital watermarking

Mourad Oussalah and Abdelhak Seriai
Site EERIE/LGI2P de l'EMA Parc Scientifique G.BESSE 30035 Nimes cedex 1 France    oussalah@eerie.fr   seriai@eerie.fr  

The formulation of queries is often regarded as a difficult task for a large class of users. In this article we propose an approach facilitating query formulation for users sharing a common database. Our approach is based on two considerations. On one hand, query formulation can be considered as a skill which can be shared entirely or partly between users. Accordingly we propose a model for storing and making available this skill to help users to formulate their new queries. On the other hand, we base our design on custom construction of a database adapted to each business group of users in question. In using it, the users of a given business cooperate transparently through their queries to design databases specific to their business. Thus, they take part co-operatively, if indirectly in reducing the difficulty of query formulation.

Keywords:Object-oriented database, query formulation, reuse, user help, cooperation

Masanobu Kobayashi, Xiaoyong Du and Naohiro Ishii
Dept. of Intelligence and Computer Science Nagoya Institute of Technology Gokiso-cho,showa-ku,Nagoya 466-8555,JAPAN    mkoba@egg.ics.nitech.ac.jp duyong@egg.ics.nitech.ac.jp ishii@egg.ics.nitech.ac.jp

Evaluating the semantic similarity of a pair of words is a basic activity in text information search and retrieval. It can, for example, be applied to query expansion to support an intelligent information retrieval system. This technique makes it easy to find relevant information from the World Wide Web (WWW) even though users cannot input all the keywords which might express their needs. For these types of systems, similarity measures are required to closely approximate human judgement. In this paper, we propose a new measure of word similarity based on the normalized information content of concepts in a semantic network. It overcomes shortcomings in existing measures. The result of experimental evaluation indicated that our measure can judge word similarity like human beings, a correlation of 0.81, which is much higher than that of existing measures.

Keywords:word similarity, semantic similarity, information content, query expansion, information retrieval

Claudio de Souza Baptista and Zarine Kemp
Computing Laboratory, University of Kent at Canterbury , Canterbury, Kent CT2 7NF UK   cdsb1@ukc.ac.uk   zk@@ukc.ac.uk

The advent of digital libraries has motivated research in some specific areas in order to apply innovative techniques to managing and retrieving information. This paper focuses on the design of spatiotemporal digital library. It presents a historical evolution of digital libraries, discusses the main requirements and issues involved in spatiotemporal digital libraries and proposes a hierarchical metadata model based on four layer of abstraction.

Keywords:digital libraries, spatiotemporal systems, multimedia, databases, metadata

Damjan Bojadziev
Department of Intelligent Systems, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia    damjan.bojadziev@ijs.si

Caplain's argument that a conscious automaton would violate a certain principle of cognition is inconclusive. Its central part has the non-demonstrative form: X is sufficient for Y because Z is not and nothing else could be. The argument and the principle are also not specific to automata.

Keywords:knowledge, reflexivity, consciousness, computation, automata

Gilbert Caplain
ENPC-CERMICS 6 & 8 avenue Blaise Pascal. Cite Descartes -- Champs-sur-Marne F-77455 Marne-la-Vallee Cedex2, FRANCE    caplain@cermics.enpc.fr  

In {Caplain95}, I have argued that consciousness cannot be adequately described as a computational structure and/or process. This argument is challenged by Damjan Bojadziev {Boj00} (this issue). This paper contains my replies and comments.

Keywords:consciousness, knowledge, belief, artificial intelligence

Enrico Nardelli
Istituto di Analisi dei Sistemi ed Informatica, Consiglio Nazionale delle Ricerche, Viale Manzoni 30, I-00185 Roma, Italia    nardelli@univaq.it

Formal methods based on the mathematical theory of partially ordered sets (i.e., posets) have been used for the description of topological relations among spatial objects since many years. In particular, the use of the lattice completion (or normal completion) of a poset modeling a set of spatial objects has been shown by Kainz, Egenhofer and Greasley to be a fundamental technique to build meaningful representations for topological relations. In a companion paper [3] we have discussed the expressive power of the lattice completion as a formal model for a set of spatial objects. In this paper we prove sufficient and necessary conditions for its use to give a correct representation of intersection and union relations among spatial objects. We also show how to use lattice completion when working on a subset (i.e., a view) of the set of spatial objects so that the computation only considers objects relevant to the view itself.

Keywords:topological model, poset, spatial relations, lattice completion

Giancarlo Fortino and Libero Nigro
Laboratorio di Ingegneria del Software Dipartimento di Elettronica Informatica e Sistemistica Universita della Calabria, I-87036 Rende (CS), Italy g.fortino@unical.it l.nigro@unical.it

This paper presents an interactive and cooperative VideoConference Recording On-demand system (ViCRO) designed for remote playback, recording and browsing multimedia sessions over the Internet MBone. It consists of Media Servers, possibly cluster-based, and Media Clients. The interaction multi-client/multi-server is based on the RTSP protocol for streaming control, on the RTP protocol for multimedia data streaming, on the LRMP protocol for reliable messaging and on the SAP protocol for group rendezvous. The time-critical and continuous components of the media clients and media servers are built by using Java and Actor based Framework (JAF), i.e., a variant of the Actor model specialised to multimedia requirements. JAF centres on timing predictability, customisable scheduling and a modular specification of QoS constraints. The main goal is to integrate MBone and WWW technologies towards media-on-demand and virtual collaborative work in heterogeneous environments. The paper introduces the Java-enabled ViCRO system and describes its application in several scenarios ranging from teleteaching to videoconferencing.

Keywords:Multimedia Modelling, VCRoD, Java, Internet MBone, RTSP, RTP, LRMP

Maria E. Orlowska
Distributed Systems Technology Centre Department of Computer Science and Electrical Engineering The University of Queensland St. Lucia, QLD 4072, Australia maria@csee.uq.edu.au

Computing multiple related group-bys and aggregates is one of the core operations of On-Line Analytical Processing (OLAP) applications. This kind of computation involves a huge volume of data operations (megabytes or treabytes). The response time for such applications is crucial, so, using parallel processing techniques to handle such computation is inevitable. In this paper we present several parallel algorithms for computing a collection of group-by aggregations based on a multiprocessor system with sharing disks. We focus on a special case of the aggregation problem-"Cube" operator which computes group-by aggregations over all possible combinations of a list of attributes. The proposed algorithms introduce a novel processor scheduling policy and a non-trivial decomposition approach for the problem in the parallel environment. Particularly, we believe the proposed hybrid algorithm has the best performance potential among the four proposed algorithms. All the proposed algorithms are scalable.

Keywords:data cube, parallel algorithms, OLAP, aggregation computation, data warehousing

I.A.R. Moghrabi and Farid Raidan
Natural Science Division, Lebanese American University, P.O. Box 13-5053 Beirut, Lebanon imoghrbi@lau.edu.lb

Of the most known natural looking objects generated by Fractal Geometry are trees. We address in this work several modified popular techniques for generating randomized naturally looking trees with non-uniformity in the pattern of generation to faithfully model irregularities in shape. In particular, we focus on L-System models for the generation of random natural phenomena. We stress statistical rather than absolute self-similarity.

Keywords:topological model, poset, spatial relations, lattice completion

Katsushi Inoue
Department of Computer Science and Systems Engineering, Faculty of Engineering, Yamaguchi University, Ube 755--8611, Japan inoue@csse.yamaguchi-u.ac.jp

Rough set theory is a powerful model for imprecise information. Inductive logic programming (ILP) is a machine learning paradigm that learns from real world environments, where the information available is often imprecise. The rough setting in ILP describes the situation where the setting is imprecise and any induced logic program will not be able to distinguish between certain positive and negative examples. The gRS-ILP model (generic Rough Set Inductive Logic Programming model) provides a framework for ILP in a rough setting. The formal definitions of the gRS--ILP model and the theoretical foundation for definitive description in a rough setting are presented. Definitive description is the description of data with 100\% accuracy and is of use in the context of Knowledge Discovery from Databases. Several declarative biases and the formation of elementary sets in a restricted \mbox{gRS--ILP} model are then studied. An illustrative experiment of the definitive description of mutagenesis data using the ILP system Progol is presented.

Keywords:Rough Set Theory, Inductive Logic Programming, Machine Learning, Knowledge Discovery from Databases