Lecture Notes in Computer Science 2563 Edited by G. Goos, J. Hartmanis, and J. van Leeuwen

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1 Lecture Notes in Computer Science 2563 Edited by G. Goos, J. Hartmanis, and J. van Leeuwen

2 3 Berlin Heidelberg New York Barcelona Hong Kong London Milan Paris Tokyo

3 Yannis Manolopoulos Skevos Evripidou Antonis C. Kakas (Eds.) Advances in Informatics 8th Panhellenic Conference on Informatics, PCI 2001 Nicosia, Cyprus, November 8-10, 2001 Revised Selected Papers 13

4 Series Editors Gerhard Goos, Karlsruhe University, Germany Juris Hartmanis, Cornell University, NY, USA Jan van Leeuwen, Utrecht University, The Netherlands Volume Editors Yannis Manolopoulos Aristotle University, Dept. of Informatics Thessaloniki, Greece Skevos Evripidou Antonis C. Kakas University of Cyprus, Dept. of Computer Science P.O. Box 20537, 1678 Nicosia, Cyprus Cataloging-in-Publication Data applied for A catalog record for this book is available from the Library of Congress Bibliographic information published by Die Deutsche Bibliothek Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at < CR Subject Classification (1998): H.2, D.2, I.2, I.4, C.2, K.3, E.1, F.2, H ISSN ISBN Springer-Verlag Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. Springer-Verlag Berlin Heidelberg New York a member of BertelsmannSpringer Science+Business Media GmbH Springer-Verlag Berlin Heidelberg 2003 Printed in Germany Typesetting: Camera-ready by author, data conversion by DA-TeX Gerd Blumenstein Printed on acid-free paper SPIN /

5 Preface The Panhellenic Conference on Informatics (PCI) was founded by the Greek Computer Society (EPY) in the early 1980s with the first event taking place in Athens in The conference has now been established as a biennial meeting of high importance for the Greek academic and industrial informatics communities, while recently the conference has been very successful in attracting significant international participation. Usually, the 8th PCI was organized in Nicosia, the capital of Cyprus, during 8 10 November 2001, in cooperation with the Cyprus Computer Society (CCS), the University of Cyprus, and the Cyprus Telecommunications Authority (CYTA). The most important factor in the decision to hold the 8th PCI in Cyprus was the aim of strengthening the existing ties between Greece and Cyprus in the academic and industrial sectors of information technology. This is particularly important in view of the imminent accession of Cyprus to the European Union. The main aim of the 8th PCI was twofold: The presentation of the most recent research work in the field of informatics carried out in Greece, Cyprus and by the Greek Diaspora, and The further promotion of information and communication technologies in Greece and Cyprus, in the broad perspective of the Information Society. In particular, the wider conference comprised the following: Twenty-three scientific sessions for refereed original research or case-study academic papers, Seven workshops of two sessions each, where non-refereed papers on applications areas of information technology were presented in a more informal setting, Three distinguished keynote speakers from government and academia, A panel on the information Society with panelists from academia and industry, An exhibition of products and services related to information and telecommunication technologies, and An industrial track where sponsors were given the opportunity to present their solutions and technologies to a professional audience. The two-volume proceedings of the conference included 104 refereed research and case-study papers accepted for presentation. Over 90% of the papers were reviewed by at least 3 referees in order to ensure a careful and fair selection of accepted papers. The 8th PCI event was therefore a very successful one in terms of the quality of contributions, program diversity, conference selectivity, and the caliber of the invited keynote speakers. For this reason, the organizers decided to publish a compendium of selected papers out of the 104 published in

6 VI Preface the conference proceedings. The present volume contains 31 selected papers that have been elaborated and extended by their authors and reviewed for a second time by two referees for each paper. We believe that this competitive procedure is a guarantee of the high quality of the outcome. During the selection process special emphasis was given to papers that deal with advances in new directions in informatics. The Internet and the World Wide Web have not only transformed informatics but they also have affected most aspects of human life, from access to information to the way we do business and the way we entertain ourselves. Thus from the pool of the best rated papers of the conference some emphasis was given towards papers that have a higher degree of relevance to the Internet and the WWW. The 31 papers in this special issue are organized into eight sections as follows: Databases, dealing with issues related to: access methods and query processing for spatial databases, the design of OLAP servers, the use of materialized views for data warehouses and the Web, extensions of SQL for spatiotemporal environments and enhancements to the two-phase commit protocol. Data Mining and Intelligent Systems, covering topics of: belief revision in the context of knowledge representation, efficient maintenance of discovered schemas for semistructured data, new clustering methods for pharmaceutical applications, adaptive classification of Web documents based on user interests, data management and mining of seismic data, and the utilization of fuzzy cognitive maps as a support system for political decision making. E-learning, including a contribution proposing an architecture for an open learning management system using state-of-the-art software engineering techniques and a contribution on the use of a knowledge-based approach to organizing and accessing educational resources. Human-Computer Interaction, investigating issues related to: website evaluation under a usability-based perspective, a conceptual framework for studying interaction in online environments with an emphasis on learning environments, as well as statistical analysis and a comparison of the accessibility ratings for different domain categories for Cyprus-related websites. Image Processing, with papers on: an information-hiding method based on the 3-coloring problem that can be used for proving copyright ownership of digital objects, an experimental evaluation of the Monte/Carlo algorithm for singular value decomposition, and a face image synthesis system. Networks and Systems, with contributions on: a methodology for building communicating X-machines from existing standalone X-machine models, task allocation onto and execution of MPI applications on parallel architectures, communication issues for data-driven multithreading mobility, and QoSprovisioninginIPv6DECTnetworks. Software and Languages, which contains three contributions dealing with: high-level timed Petri Net temporal verification of real-time multiprocessor applications, architectural and application issues of a Greek morphological lexicon, and design patterns and roles in the context of behavioural evolution.

7 Preface VII Theoretical Issues, containing four papers focusing on: a new randomized data structure for the 1.5-dimensional range query problem, acceptor definable counting classes, the stability behaviour of the FIFO protocol in the adversarial queuing model, and a formal proof that k-splay fails to achieve base-k logn behavior. We thank Springer-Verlag for accepting to publish this volume and for helping us make it a reality. We anticipate that this support will help in increasing further the quality of the PCI conference and we hope that this collaboration will continue in the future. Finally, the papers of this volume would not have met the desired standard of high quality without the invaluable help of the referees, all of whom we thank very much. February 2003 Yannis Manolopoulos Skevos Evripidou Antonis C. Kakas

8 Reviewers Andreas Andreou, University of Cyprus Nikolaos Avouris, University of Patras Panagiotis Bozanis, University of Thessaly Vassilis Christofides, University of Crete Stavros Dimitriadis, Aristotle University of Thessaloniki Petros Drineas, Yale University George Eleftherakis, City Liberal Studies Thessaloniki George Evangelidis, University of Macedonia, Thessaloniki George Hassapis, Aristotle University of Thessaloniki Yannis Ioannidis, National and Kapodistrian University of Athens Dimitrios Katsaros, Aristotle University of Thessaloniki Petros Kefalas, City Liberal Studies Thessaloniki Evangelos Kehris, City Liberal Studies Thessaloniki Constantine Kotropoulos, Aristotle University, Thessaloniki Nectarios Koziris, National Technical University of Athens Evangellos Markatos, University of Crete Pericles Mitkas, Aristotle University of Thessaloniki Costas Mourlas, University of Athens Alexandros Nanopoulos, Aristotle University of Thessaloniki George Papadimitriou, Aristotle University of Thessaloniki Nikolaos Papaspyrou, National Technical University of Athens Iraklis Paraskakis, City Liberal Studies Thessaloniki Andreas Pitsillides, University of Cyprus Simos Retalis, University of Cyprus Dimitrios Sampson, Inst. of Telecom and Informatics Thessaloniki Paul Spirakis, University of Patras Ioannis Stamelos, Aristotle University of Thessaloniki Yannis Stavrakas, NCSR Democritos, Athens Yannis Theodoridis, University of Piraeus Athanasios Tsakalidis, University of Patras Michael Vassilakopoulos, Higher TEI of Thessaloniki Panos Vassiliadis, University of Ioannina Michael Vazyrgiannis, Athens University of Economics and Business Ioannis Vlahavas, Aristotle University of Thessaloniki Stathis Zachos, National Technical University of Athens

9 Table of Contents Processing Distance-Based Queries in Multidimensional Data Spaces Using R-trees...1 Antonio Corral, Joaquin Cañadas, and Michael Vassilakopoulos A Simple, Compact and Dynamic Partition Scheme Based on Co-centric Spheres Dimitris G. Kapopoulos and Michael Hatzopoulos Design of the ERATOSTHENES OLAP Server...32 Nikos Karayannidis, Aris Tsois, Panos Vassiliadis, and Timos Sellis Spatio-temporal SQL...50 José R. Rios Viqueira and Nikos A. Lorentzos The Opsis Project: Materialized Views for Data Warehouses and the Web...64 Nick Roussopoulos, Yannis Kotidis, Alexandros Labrinidis, and Yannis Sismanis Two-Phase Commit Processing with Restructured Commit Tree George Samaras, George K. Kyrou, and Panos K. Chrysanthis On the Use of Matrices for Belief Revision Giorgos Flouris and Dimitris Plexousakis Efficiently Maintaining Structural Associations of Semistructured Data Dimitrios Katsaros Identification of Lead Compounds in Pharmaceutical Data Using Data Mining Techniques Christodoulos A. Nicolaou Adaptive Classification of Web Documents to Users Interests George Potamias Seismo-Surfer: A Prototype for Collecting, Querying, and Mining Seismic Data Yannis Theodoridis Using Fuzzy Cognitive Maps as a Decision Support System for Political Decisions Athanasios K. Tsadiras, Ilias Kouskouvelis, and Konstantinos G. Margaritis An Architecture for Open Learning Management Systems Paris Avgeriou, Simos Retalis, and Manolis Skordalakis

10 X Table of Contents A Knowledge Based Approach on Educational Metadata Use Fotios Kokkoras, Dimitrios Sampson, and Ioannis Vlahavas Website Evaluation: A Usability-Based Perspective Nikolaos Avouris, Nikolaos Tselios, Christos Fidas, and Eleftherios Papachristos Concepts to Consider when Studying Computer-Mediated Communication and Online Learning Charalambos Vrasidas Website Content Accessibility of the Cyprus Domain Panayiotis Zaphiris and Giorgos Zacharia An Information Hiding Method Based on Computational Intractable Problems Spyridoula M. Armeni, Dimitris N. Christodoulakis, Ioannis Kostopoulos, Polychronis D. Kountrias, Yannis C. Stamatiou, and Michalis Xenos An Experimental Evaluation of a Monte-Carlo Algorithm for Singular Value Decomposition Petros Drineas, Eleni Drinea, and Patrick S. Huggins PROSOPO A Face Image Synthesis System Andreas Lanitis Communicating X-Machines: From Theory to Practice Petros Kefalas, George Eleftherakis, and Evangelos Kehris TOPPER: An Integrated Environment for Task Allocation and Execution of MPI Applications onto Parallel Architectures Dimitris Konstantinou and Nectarios Koziris Communication Assist for Data Driven Multithreading Costas Kyriacou and Paraskevas Evripidou A Framework for Mobility and QoS Provisioning in IPv6 DECT Networks Sarantis Paskalis, Georgios Lampropoulos, Dimitris Skyrianoglou, and Evangelos Zervas High Level Timed Petri Net Templates for the Temporal Verification of Real-Time Multiprocessor Applications Dimitra Ananidou, George Hassapis, and Dimitrios Kleftouris A Greek Morphological Lexicon and Its Exploitation by Natural Language Processing Applications Georgios Petasis, Vangelis Karkaletsis, Dimitra Farmakiotou, Ion Androutsopoulos, and Constantine D. Spyropoulo A Comparison of Design Patterns and Roles in the Context of Behavioural Evolution Dimitrios Theotokis, Anya Sotiropoulou, George Gyftodimos, and Panagiotis Georgiadis

11 Table of Contents XI A New Randomized Data Structure for the 1 1/2-dimensional Range Query Problem Panayiotis Bozanis Acceptor-Definable Counting Classes Aggelos Kiayias, Aris Pagourtzis, Kiron Sharma, and Stathis Zachos Stability Behavior of FIFO Protocol in the Adversarial Queuing Model Dimitrios K. Koukopoulos, Sotiris E. Nikoletseas, and Paul G. Spirakis Sphendamnœ: A Proof that k-splay Fails to Achieve log k N Behaviour D.J. McClurkin and G.F. Georgakopoulos Author Index...497