Journal of Applied Logic 5 (2007) 389–391

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Editorial

Special Issue arising from the 9th European Conference on Logics inArtificial Intelligence, JELIA’2004

This special issue of the Journal of Applied Logic contains extended versions of a selection of papers presentedat the 9th European Conference on Logics in Artificial Intelligence, JELIA’04, which took place in Lisbon, Portugal,between the 27th and the 30th of September 2004, and was hosted by the Universidade Nova de Lisboa.

The European Conference on Logics in Artificial Intelligence (or Journées Européennes sur la Logique en Intelli-gence Artificielle—JELIA) began back in 1988, as a workshop, in response to the need for a European forum for thediscussion of emerging work in this field. Since then, JELIA has been organised biennially. The increasing interest inthis forum, its international level with growing participation from researchers outside Europe, and the overall techni-cal quality, has turned JELIA into a major biennial forum for the discussion of logic-based approaches to ArtificialIntelligence.

The six papers that constitute this special issue cover various aspects of the application of Logics as the formal basisfor Artificial Intelligence, and result from a selection process that started with the 144 papers submitted to JELIA’04,a number which, together with the 25 system description submissions, clearly indicates that the research area of Logicsin AI is one with great and increasing interest. Of these 144 papers, 52 were selected by the Program Committee forpresentation at the conference. A selection of 11 were invited to submit revised and extended versions of their papersfor possible inclusion in this special issue. Of those that accepted the invitation, and after another thorough round ofreviewing, 6 were finally selected for publication.

The first paper in this volume, entitled Computing the least common subsumer w.r.t. a background terminology andco-authored by Franz Baader, Baris Sertkaya and Anni-Yasmin Turhan, discusses a (non-standard) reasoning task forDescription Logics: computing least common subsumer, which is the most specific concept description that subsumessome given concept descriptions. The computation of these subsumers is highly relevant in practice, as they naturallybecome candidate descriptions to be incorporated in an existing ontology, when such ontology is to be extended in anexample-driven way.

The volume continues with a paper on Spacial Reasoning, by Philippe Balbiani and Tinko Tinchev, entitled Line-based affine reasoning in Euclidean plane, where the authors give a rigorous technical development of reasoningabout lines in affine Euclidean planes, together with complexity results. More precisely, the authors show that rea-soning about these structures is NP complete for modal logics and PSPACE complete for first order theories of thesestructures.

The third paper, by Carlos Viegas Damásio, Jesus Medina and Manuel Ojeda-Aciego, is entitled Terminationof logic programs with imperfect information: applications and query procedure, and presents a very general logicprogramming framework that allows for the combination of several adjoint lattices of truth-values, enabling the combi-nation of several reasoning forms in a knowledge base. The paper concentrates on operational issue for this framework,especially on termination properties.

The volume continues with two papers dedicated to Belief Revision.The first of these two papers is entitled A consistency-based framework for merging knowledge bases and is co-

authored by James Delgrande and Torsten Schaub. The authors describe two approaches to merging propositionalknowledge bases, using ideas arising from previous work on belief revision. The knowledge bases to be merged arefirst expressed in different propositional languages, and links between the languages are added as maximal sets of

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390 Editorial / Journal of Applied Logic 5 (2007) 389–391

equivalences between atoms. The two approaches differ in the way links between the languages are defined, and bothare shown to satisfy postulates that were previously proposed in the literature.

The second paper related to Belief Revision is authored by Lee Flax, and is entitled An algebraic approach tobelief contraction and nonmonotonic entailment. With the goal of shedding light on the process of revision and onproviding a means to compute it, the paper recasts the well know Alchourrón, Gärdenfors and Makinson (AGM) beliefcontraction in algebraic terms using a preboolean algebra. The paper provides a thorough treatment and offers somenew insights into the process of belief revision. Most importantly, the paper provides a significant clue on how onecould implement belief revision in a structured manner.

The last paper in this volume, Only knowing with degrees of confidence, by Aril Waller, Johan Klüwer, Tore Lang-holm and Espen Lian, presents a non-monotonic logic of belief that deals with confidence levels. The logics belongsto the so-called “only knowing” family, initiated by Levesque. Compared to previous work, this logics introduces aricher set of epistemic concepts, both for the description of the system itself and for use in representation of common-sense patterns of reasoning, and has an increased expressive power which enables the representation of a certain sortof prioritized defaults. The logics is closed under uniform substitution and is axiomatized entirely at the object-level.

With the depth and maturity of formalisms, methodologies and logic-based systems, the claim that Logics providean ideal formal basis for the study and development of applications and systems in Artificial Intelligence is, today,stronger than ever. The technical content of JELIA’04 and the papers in this special issue are just pieces of evidenceto support this claim.

We would like to thanks the authors of all the contributions that were submitted to JELIA’04, the members of theProgram Committee and the additional experts who helped throughout the two-stage reviewing process, for contribut-ing and ensuring the high scientific quality of JELIA’04 and this special issue.

Conference ChairJoão Leite Universidade Nova de Lisboa, Portugal

Program ChairJosé Júlio Alferes Universidade Nova de Lisboa, Portugal

Program CommitteeJosé Júlio Alferes Universidade Nova de Lisboa, PortugalFranz Baader TU Dresden, GermanyChitta Baral Arizona State University, USASalem Benferhat Université d’Artois, FranceAlexander Bochman Holon Academic Institute of Technology, IsraelRafael Bordini University of Durham, UKGerhard Brewka University of Leipzig, GermanyWalter Carnielli Universidade Estadual de Campinas, BrazilLuis Fariñas del Cerro Université Paul Sabatier, FranceMehdi Dastani Universiteit Utrecht, The NetherlandsJames Delgrande Simon Fraser University, CanadaJürgen Dix TU Clausthal, GermanyRoy Dyckhoff University of St Andrews, UKThomas Eiter TU Wien, AustriaPatrice Enjalbert Université de Caen, FranceMichael Fisher University of Liverpool, UKUlrich Furbach University Koblenz-Landau, GermanyMichael Gelfond Texas Tech University, USASergio Greco Università della Calabria, ItalyJames Harland Royal Melbourne Institute Technology, AustraliaJoão Leite Universidade Nova de Lisboa, PortugalMaurizio Lenzerini Università di Roma “La Sapienza”, ItalyNicola Leone Università della Calabria, Italy

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Vladimir Lifschitz University of Texas at Austin, USAMaarten Marx Universiteit van Amsterdam, The NetherlandsJohn-Jules Meyer Universiteit Utrecht, The NetherlandsBernhard Nebel Universität Freiburg, GermanyIlkka Niemelä Helsinki University of Technology, FinlandManuel Ojeda-Aciego Universidad de Málaga, SpainDavid Pearce Universidad Rey Juan Carlos, SpainLuís Moniz Pereira Universidade Nova de Lisboa, PortugalHenri Prade Université Paul Sabatier, FranceHenry Prakken Universiteit Utrecht, The NetherlandsLuc de Raedt Universität Freiburg, GermanyKen Satoh National Institute of Informatics, JapanRenate Schmidt University of Manchester, UKTerrance Swift SUNY at Stony Brook, USAFrancesca Toni Imperial College, UKPaolo Torroni Università di Bologna, ItalyMirek Truszczynski University of Kentucky, USAHudson Turner University of Minnesota, USAWiebe van der Hoek University of Liverpool, UKToby Walsh University College Cork, IrelandMary-Anne Williams The University of Technology, Sydney, AustraliaMichael Zakharyaschev King’s College, UK

Additional ReviewersUlrich Hustadt Luis Lamb

Guest Editors

José Júlio Alferes ∗João Leite

E-mail address: jja@di.fct.unl.pt (J.J. Alferes)

Available online 3 May 2006

* Corresponding author.