since March 20, 1997.

Koblenz Landau
DFG Bonn

DisLoP: a research project on Disjunctive Logic Programming

Funding * Persons * Activities * Systems * Publications * Related Projects * Related Links

The research project on Disjunctive Logic Programming, referred to as DisLoP, was initiated in July 1995 at the University of Koblenz, Germany, by Jürgen Dix and Ulrich Furbach. An initial funding for two years was provided by Deutsche Forschungsgemeinschaft (DFG) (under grant Fu 263/3-1). Two research scientists Chandrabose Aravindan and Ilkka Niemelä worked exclusively on this project for two years (1995 - 1997). After a detailed evaluation of the project, DFG has extended the funding until 2000 (under grant Fu 263/3-2). Currently, three scientists are employed in this project: Ingo Dahn, Micha Kühn and Bernd Thomas.

The main aim of this project is to develop semantics and procedures for dealing with disjunction and non-monotonic negation in logic programming. On the procedural side, instead of starting from scratch, the aim is to exploit the techniques that have been developed for yet another project on Automated Reasoning (that was led led 3 years ago in Koblenz by Ulrich Furbach as a part of the German ``Schwerpunkt-Programm'' Deduction). One important consequence of this is that the PROTEIN theorem prover developed during the course of the Deduction project can be used for (positive) Disjunctive Logic Programming with little modifications. DisLoP also aims to apply the developed concepts and systems in real world applications such as Information Management Systems. This, by itself, has been conceived as a separate project, and thus there are three inter-related and co-operating projects at the University of Koblenz, Germany.

Interested visitors can go through the project report of phase 1995-97 DISLOP: A research Project on Disjunctive Logic Programming that highlights salient features of this project and summarizes the results (appeared in: AI Communications Vol. 10, No. 3/4*151--165, 1997).


This project is funded (under grants Fu 263/3-1 and Fu 263/3-2) by Deutsche Forschungsgemeinschaft (DFG), a federal government agency that funds various basic research projects in Germany.

Persons Involved

The project is headed by Dr. Jürgen Dix. and Prof.Dr. Ulrich Furbach. Two research scientists Dr. Ilkka Niemelä and Dr. Chandrabose Aravindan worked exculsively on this project from 1995 to 1997. Currently, three scientists are employed in this project: Ingo Dahn, Micha Kühn and Bernd Thomas.



  • Theorem prover PROTEIN now supports minimal model reasoning based on negation by failure to explain.
  • mm is a tableau-based minimal model reasoner written in ECLiPSe Prolog by Dr. Ilkka Niemelä and Katrin Erk.
  • We have developed a system for generating test cases from NP-complete graph problems. Currently, the test cases are positive ground programs (i.e. ground clauses) and provide challenging test material for minimal model and other propositional reasoners. Test case can be generated using this form.
  • Another set of interesting test cases are the ISCAS-85 benchmarks.
  • dwfs transforms a disjunctive logic program into a residual, from which the D-WFS semantics can be read off directly. dwfs has been written in ECLiPSe Prolog by Katrin Erk.
  • dwfs-mm is an extension of mm which computes D-WFS semantics using iterative minimal model reasoning.
  • Constraint D-WFS is an extension, based on constraints, of the D-WFS semantics for the first-order case.

Recent Publications

Some of the recent publications of the members of this project are listed below. The complete list of local technical reports is maintained by Peter Baumgartner.

  • Frieder Stolzenburg:, A flexible system for constraint disjunctive logic programming.
    KI, 12(2):73-78, 1998.
    Abstract. Extended version appeared as Fachberichte Informatik 19/96.
  • Stefan Brass and Jürgen Dix: Characterizations of the Disjunctive Well-founded Semantics: Confluent Calculi and Iterated GCWA. Journal of Automated Reasoning, 20(1):143-165, 1998. (Extended abstract appeared in: newblock Characterizing D-WFS: Confluence and Iterated GCWA. newblock Logics in Artificial Intelligence, JELIA '96, pages 268-283, 1996. Springer, LNCS 1126.).
  • Stefan Brass, Jürgen Dix, Ilkka Niemelä, and Teodor. C. Przymusinski: A Comparison of the Static and the Disjunctive Well-founded Semantics and its Implementation. In A. G. Cohn, L. K. Schubert, and S. C. Shapiro, editors, Principles of Knowledge Representation and Reasoning: Proceedings of the Sixth International Conference (KR '98), pages 74-85. San Francisco, CA, Morgan Kaufmann, May 1998. appeared also as TR 17/97, University of Koblenz.
  • Gerhard Brewka and Jürgen Dix: Knowledge representation with logic programs. In J. Dix, L. Pereira, and T. Przymusinski, editors, Logic Programming and Knowledge Representation, LNAI 1471, pages 1-55, Berlin, 1998. Springer.
  • Stefan Brass and Jürgen Dix, Characterizations of the disjunctive stable semantics by partial evaluation. Journal of Logic Programming, 32(3):207-228, 1997.
  • Stefan Brass and Jürgen Dix, Characterizations of the disjunctive well-founded semantics: Confluent calculi and iterated GCWA, Journal of Automated Reasoning, 1997.
  • Stefan Brass and Jürgen Dix, Semantics of disjunctive logic programs based on partial evaluation. Journal of Logic Programming, 1997.
  • Jürgen Dix and Frieder Stolzenburg, Computation of non-ground disjunctive well-founded semantics with constraint logic programming. In Jürgen Dix, Luís Moniz Pereira, and Teodor C. Przymusinski, editors, Selected Papers of the Workshop on Non-Monotonic Extensions of Logic Programming in Conjunction with Joint International Conference and Symposium on Logic Programming 1996, LNAI 1216, pages 202-226, Bad Honnef, 1997. Springer, Berlin, Heidelberg, New York.
  • Jürgen Dix and Frieder Stolzenburg: A framework to incorporate non-monotonic reasoning into constraint logic programming. Journal of Logic Programming, 37(1-3):47-76, 1998. Special Issue on Constraint Logic Programming, Guest Editors: Kim Marriott and Peter Stuckey.
  • J. Dix, L. Farinas del Cerro, and U. Furbach, editors: Logics in Artificial Intelligence, number 1489 in LNCS, Berlin, 1998. Springer.
  • J. Dix, L. Pereira, and T. Przymusinski, editors: Logic Programming and Knowledge Representation, LNAI 1471, Berlin, 1998. Springer.
  • Jürgen Dix. The Logic Programming Paradigm. AI Communications, Vol. 11, No. 3:39-43, 1998.
  • S. Brass, J. Dix, I. Niemelä and T. Przymusinski, A Comparison of the Static and the Disjunctive WFS and its Implementation
    Proc. of the Sixth Intern. Conf. on Principles of Knowledge Repr. and Reasoning (KR '98),
    A.G. Cohn and L.K. Schubert and S.C. Shapiro (eds.), Morgan Kaufmann, San Francisco 1998.
  • Jürgen Dix, Frieder Stolzenburg, A Framework to Incorporate Non-Monotonic Reasoning into Constraint Logic Programming, Research Report 16-97. (Abstract, Report )
  • Stefan Brass, Jürgen Dix, Teodor Przymusinski, Super Logic Programs, Research Report 12-97. (Abstract, Report )
  • Jürgen Dix, Mauricio Osorio, Towards Well-Behaved Semantics Suitable for Aggregation, Research Report 11-97. (Abstract, Report )
  • Chandrabose Aravindan and Peter Baumgartner, A Rational and Efficient Algorithm for View Deletion in Databases, Research Report 10-97. (Abstract, Report )
  • Jürgen Dix, Luis Pereira, Teodor Przymusinski, Prolegomena to Logic Programming for Non-Monotonic Reasoning, Research Report 4-97. (Abstract, Report )
  • Ulrich Furbach, A View to Automated Reasoning in Artificial Intelligence, Research Report 2-97. (Abstract, Report )
  • Chandrabose Aravindan, Jürgen Dix, Ilkka Niemelä, DisLoP: A Research Project on Disjunctive Logic Programming, Research Report 1-97. (Abstract, Report )
  • Peter Baumgartner, Ulrich Furbach, and Frieder Stolzenburg, Computing answers with model elimination, Artificial Intelligence, 90(1-2):135-176, 1997.
  • Peter Baumgartner, Peter Fröhlich, Ulrich Furbach, Wolfgang Nejdl, Tableaux for Diagnosis Applications, Research Report 23-96. (Abstract, Report )
  • Wenjin Lue, Minimal Model Generation Based on E-Hyper Tableaux, Research Report 20-96. (Abstract, Report )
  • Frieder Stolzenburg, A Flexible System for Constraint Disjunctive Logic Programming, Research Report 19-96. (Abstract, Report )
  • Chandrabose Aravindan, DisLoP: A disjunctive logic programming system based on PROTEIN theorem prover, Research Report 16-96. (Abstract, Report)
  • Jürgen Dix, Gerhard Brewka, Knowledge representation with logic programs, Research Report 15-96. (Abstract, Report)
  • Peter Baumgartner, Ulrich Furbach, Hyper Tableaux and Disjunctive Logic Programming, Research Report 13-96. (Abstract, Report)
  • Chandrabose Aravindan, An abductive framework for negation in disjunctive logic programming, Research Report 9-96. (Abstract, Report)
  • Ilkka Niemelä, Patrik Simons, Efficient Implementation of the Well-founded and Stable Model Semantics, Research Report 7-96. (Abstract, Report)
  • Ilkka Niemelä, Implementing Circumscription Using a Tableau Method, Research Report 6-96. (Abstract, Report)
  • Ilkka Niemelä, A tableau calculus for minimal model reasoning, Research Report 5-96. (Abstract, Report)
  • Stefan Brass, Jürgen Dix, Teodor C. Przymusinski, Characterizations and Implementation of Static Semantics of Disjunctive Programs, Research Report 4-96. (Abstract, Report)
  • Stefan Brass, Jürgen Dix, Ilkka Niemelä, Teodor C. Przymusinski, A Comparison of Static Semantics and D-WFS, Research Report 2-96. (Abstract, Report)
  • J. Dix, D. Gottlob, V. Marek, Reducing disjunctive to non-disjunctive semantics by shift operations, Research report 18-95. (Abstract, Report)
  • P. Baumgartner, J. Dix, U. Furbach, D. Schäfer, F. Stolzenburg, Deduktion und Logisches Programmieren. KI, 10(2):34-39, 1996. Also available as Research Report 17-95. (Abstract, Report)
  • S. Brass, J. Dix, D-WFS: A Confluent Calculus and an Equivalent Characterization, Research Report 12-95. (Abstract, Report)
  • Peter Baumgartner, Ulrich Furbach, and Frieder Stolzenburg, Model elimination, logic programming and computing answers, In Proceedings of the 14th International Joint Conference on Artificial Intelligence, pages 335-340, Montréal, 1995. Volume 1.

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Last modified: Fri Jun 15 20:16:57 CEST 2001
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