2008 | 2007 | 2006 | 2005 | 2004 | 2003 | 2001 | 1999 | 1998 | 1991

2008

  • Anastasia Analyti, Grigoris Antoniou, Carlos Viegas Damasio and Gerd Wagner. On the Computability and Complexity Issues of Extended RDF. Proceedings of the Tenth Pacific Rim International Conference on Artificial Intelligence (PRICAI 08). Springer Verlag. 2008. LNAI. pdf-download. Extended RDF ontologies, Semantic Web, negation, rules, complexity
  • Anastasia Analyti, Grigoris Antoniou, Carlos Viegas Damasio and Gerd Wagner. Extended RDF as a Semantic Foundation of Rule Markup Languages. Journal of Artificial Intelligence Research. 2008. volume 32. pp. 37–94. download
  • Ion Mircea Diaconescu, Adrian Giurca, Gerd Wagner and Jens Dietrich. In: G. J. Nalepa and J. Baumeister (Eds.). Towards a Mapping from ERDF(S) to Take Vocabulary. Proceedings of 4th Workshop on Knowledge Engineering and Software Engineering. CEUR Workshop Proceedings. September, 23-26-2008. Kaiserslautern, Germany
  • Jens Dietrich, Bastian Schenke and Gerd Wagner. On Code Generation for Derived Associations. Proceedings of the 19th Australian Conference on Software Engineering (ASWEC 2008). IEEE Computer Society Press. March, 26-28-2008. Perth, Australia
  • Adrian Giurca, Ion Mircea Diaconescu, Emilian Pascalau and Gerd Wagner. In: Giuseppe Mangioni and Costin Badica (Eds.). On the Foundations of Web based Registries for Business Rules. Proceedings of 2nd International Symposium on Intelligent Distributed Computing. Springer. September, 18-19-2008. volume 162. Studies in Computational Intelligence. Catania, Italy
  • Oana Nicolae, Mirel Cosulschi, Adrian Giurca and Gerd Wagner. Towards a BPMN Semantics using UML Models. Proceedings of 2nd International Workshop on Collaborative Business Processes (CBP). Springer Verlag. September, 1-4-2008. LNBIP. Milano, Italy. pdf-download
  • Oana Nicolae, Adrian Giurca and Gerd Wagner. On Interchange between JBossRules and Jess. Special issue of International Journal of Computing and Informatics Intelligent and Distributing Computing . 2008. volume 32. number: 4
  • Oana Nicolae and Gerd Wagner. Verbalising R2ML rules into SBVR. Proc. of 10th International Symposium on Symbolic and Numeric Algorithms for Scientific Computing (SYNASC 2008). IEEE. September, 26 29-2008. Timisoara, Romania. pdf-download
Technical reports
  • Gerd Wagner, Adrian Giurca, Ion Mircea Diaconescu, Grigoris Antoniou and Carlos Viegas Damasio. ERDF Implementation and Evaluation. REWERSE IST 506779 Report I1 D14. Mar-2008. pdf-download

2007

  • Ion Mircea Diaconescu and Gerd Wagner. Towards a Mapping from Java Vocabulary to RDFS. Proc. of 1st East European Workshop on Rule Based Applications. IEEE Computer Society. Sep-2007. pp. 518–522. Timisoara, Romania. pdf-download. digital identifier
  • Adrian Giurca and Gerd Wagner. Rule Modeling and Interchange. Proc. of 9th International Symposium on Symbolic and Numeric Algorithms for Scientific Computing. IEEE Computer Society. Sep-2007. pp. 485–491. Los Alamitos, CA, USA. digital identifier
  • Nima Kaviani, Dragan Gasevic, Marek Hatala, David Clement and Gerd Wagner. Integration of rules and policies for Semantic Web Services. Int. J. Advanced Media and Communication. 2007. volume 1. pp. 404–423. number: 4
  • Nima Kaviani, Dragan Gasevic, Marek Hatala and Gerd Wagner. Web Rule Languages to Carry Policies. Proceedings of the 8th IEEE International Workshop on Policies for Distributed Systems and Networks. 2007. pp. 188–192. Bologna, Italy. digital identifier
  • Nima Kaviani, Dragan Gasevic, Marek Hatala, Gerd Wagner and Timmy Eap. Exchanging Policies between Web Service Entities using Rule Languages. Proceedings of the 2007 IEEE Congress on Services (SERVICES 2007), in conjunction with, the 2007 IEEE International Conference on Web Services (ICWS 2007). 9 13 July-2007. pp. 57–64. Salt Lake City, Utah, USA
  • Sergey Lukichev, Adrian Giurca and Gerd Wagner. An Integrated Rule Modeling Framework. INFORMATIK 2007. Informatik trifft Logistik. Beitraege der 37. Jahrestagung der Gesellschaft fuer Informatik e.V. (GI). GI. Sep-2007. volume 109. Bremen, Germany
  • Sergey Lukichev, Adrian Giurca, Gerd Wagner, Dragan Gasevic and Marko Ribaric. In: Vincent Oria, Ahmed Elmagarmid, Fred Lochovsky and Yucel Saygin (Eds.). Using UML based Rules for Web Services Modeling. Proceedings of the Second International Workshop on Services Engineering. IEEE Computer Society. 16 April-2007. pp. 290–298. Istanbul, Turkey
  • Milan Milanovic, Dragan Gasevic, Adrian Giurca, Gerd Wagner and Vladan Devedzic. Model Transformations to Share Rules between SWRL and R2ML. Proceedings of 3rd International Workshop on Semantic Web Enabled Software Engineering (SWESE 2007). 6 June-2007. Innsbruck, Austria. pdf-download
  • Milan Milanovic, Dragan Gasevic, Adrian Giurca, Gerd Wagner, Sergey Lukichev and Vladan Devedzic. In: M. Marchiori, J.Z. Pan and C. de Sainte Marie (Eds.). Bridging Concrete and Abstract Syntax of Web Rule Languages. Proceedings of 1st International Conference on Web Reasoning and Rule Systems (RR'2007). Springer. 7 8 June-2007. pp. 309–318. Innsbruck, Austria. pdf-download
  • Milan Milanovic, Nima Kaviani, Dragan Gasevic, Adrian Giurca, Gerd Wagner, Vladan Devedzic and Marek Hatala. Business Process Integration by using General Rule Markup Language. The 11th IEEE International Enterprise Distributed Object Computing Conference (EDOC 2007). 15 19 October-2007. pp. 353–364. Annapolis, Maryland, USA
  • Oana Nicolae, Ion Mircea Diaconescu, Adrian Giurca and Gerd Wagner. Sharing rules between JBoss and Jena. Proc. of 9th International Symposium on Symbolic and Numeric Algorithms for Scientific Computing. IEEE Computer Society. September, 26 29-2007. pp. 105–108. Timisoara, Romania. pdf-download. digital identifier
  • Oana Nicolae, Ion Mircea Diaconescu, Adrian Giurca and Gerd Wagner. In: Ion Iancu and Nicolae Tandareanu (Eds.). Towards a Financial Service implementation using Jena and JBoss. Proceedings of the 7th International Conference on Artificial Intelligence and Digital Communication. September, 15-16-2007. pp. 59–69. Craiova, Romania. pdf-download
  • Oana Nicolae, Adrian Giurca and Gerd Wagner. In: C. Badica and M. Paprzycki (Eds.). On Interchange between JBossRules and Jess. Proceedings of 1st International Symposium on Intelligent and Distributed Computing. Springer. October, 18-20-2007. Studies in Computational Intelligence. Craiova, Romania. pdf-download
Technical reports
  • Sergey Lukichev, Adrian Giurca, Gerd Wagner and Marko Ribaric. Tool Improvements and Extensions 1. REWERSE IST 506779 Report I1 D10. Mar-2007. Munchen, Germany. pdf-download
  • Sergey Lukichev, Gerd Wagner and Norbert E. Fuchs. Tool Improvements and Extensions 2. REWERSE IST 506779 Report I1 D11. Mar-2007. pdf-download
  • Gerd Wagner, Adrian Giurca, Sergey Lukichev, Oana Nicolae and Ion Mircea Diaconescu. Case Study 1: Userv product Derby 2005. REWERSE IST 506779 Report I1 D9. Mar-2007. pdf-download

2006

  • Uwe Assmann, Steffen Zschaler and Gerd Wagner. In: Coral Calero, Francisco Ruiz and Mario Piattini (Eds.). Ontologies for Software Engineering and Technology. Springer Verlag. 2006. Ontologies, Metamodels, and the Model Driven Paradigm. pp. 249–274. pdf-download
  • Costin Badica, Adrian Giurca and Gerd Wagner. In: Dirk Draheim and Gerald Weber (Eds.). Using Rules and R2ML for Modeling Negotiation Mechanisms in E Commerce Agent Systems. Proceedings of the 2nd International Conference on Trends in Enterprise Application Architecture, TEAA2006. Springer. Nov-2006. volume 4473. pp. 84–99. Lecture Notes in Computer Science. pdf-download
  • Carlos Viegas Damasio, Anastasia Analyti, Grigoris Antoniou and Gerd Wagner. In: Jose Julio Alferes, James Bailey, Wolfgang May and Uta Schwertel (Eds.). Supporting Open and Closed World Reasoning on the Web. Principles and Practice of Semantic Web Reasoning. Springer Berlin/Heidelberg. 10 11 June-2006. volume 4187. pp. 149–163. Lecture Notes in Computer Science. Budva, Montenegro. digital identifier
  • Dragan Gasevic, Adrian Giurca, Sergey Lukichev and Gerd Wagner. Rule Based Modeling of Semantic Web Services. Proceedings of 2nd International Workshop on Semantic Web Enabled Software Engineering (SWESE 2006). 5 9 November-2006. Athens, GA, U.S.A. pdf-download
  • Adrian Giurca, Sergey Lukichev and Gerd Wagner. Modeling Web Services with URML. Proceedings of SBPM'2006. 11 May-2006. Budva, Montenegro. pdf-download
  • Nima Kaviani, Dragan Gasevic, Marek Hatala, David Clement and Gerd Wagner. Towards Unifying Rules and Policies for Semantic Web Services. Proceedings of the 3rd annual e learning conference on Intelligent Interactive Learning Object Repositories. Nov-2006. Montreal, Canada
  • Sergey Lukichev and Gerd Wagner. In: Irina Virbitskaite and Andrei Voronkov (Eds.). Visual Rules Modeling. Proceedings of the 6th International Conference Perspectives of Systems Informatics. Springer. 2006. volume 4378. pp. 467–673. Lecture Notes in Computer Science. pdf-download
  • Sergey Lukichev and Gerd Wagner. In: Holger Giese and Bernhard Westfechtel (Eds.). UML Based Rule Modeling with Fujaba. Proceedings of the 4th International Fujaba Days 2006, University of Bayreuth, Germany. 28 30 September-2006. pp. 31–35. pdf-download
  • Milan Milanovic, Dragan Gasevic, Adrian Giurca, Gerd Wagner and Vladan Devedzic. On Interchanging Between OWL/SWRL and UML/OCL. Proceedings of the OCLApps Workshop. 2 October-2006. pp. 81–95. Genova, Italy. pdf-download
  • Milan Milanovic, Dragan Gasevic, Adrian Giurca, Gerd Wagner and Vladan Devedzic. Sharing OWL/SWRL and UML/OCL Rules. Proceedings of ACM/IEEE 9th International Conference on Model Driven Engineering Languages and Systems (MODELS 2006). 1 6 October-2006. Genova, Italy. pdf-download
  • Milan Milanovic, Dragan Gasevic, Adrian Giurca, Gerd Wagner and Vladan Devedzic. Towards Sharing Rules between OWL/SWRL and UML/OCL. Electronic Communications of the EASST. 2006. volume 5. download
  • Adrian Paschke, Jens Dietrich, Adrian Giurca, Gerd Wagner and Sergey Lukichev. On Self Validating Rule Bases. Proceedings of 2nd International Workshop on Semantic Web Enabled Software Engineering (SWESE 2006). 5 9 November-2006. Athens, GA, U.S.A. pdf-download
  • Gerd Wagner, Adrian Giurca and Sergey Lukichev. A Usable Interchange Format for Rich Syntax Rules Integrating OCL, RuleML and SWRL. Proceedings of Reasoning on the Web. 22 May-2006. Edinburgh, Scotland. pdf-download
Technical reports
  • Sergey Lukichev and Gerd Wagner. XML Code Generation Component for the I1 Rule Modeling Tool. REWERSE IST 506779 Report I1 D5. Sep-2006. pp. 27. Munchen, Germany. pdf-download
  • Sergey Lukichev and Gerd Wagner. Verbalization of the REWERSE I1 Rule Markup Language. REWERSE IST 506779 Report I1 D6. Sep-2006. pp. 37. pdf-download
  • Gerd Wagner, Sergey Lukichev, Adrian Giurca, Adrian Paschke and Jens Dietrich. Verification and Validation of R2ML Rule Bases. REWERSE IST 506779 Report I1 D7. Sep-2006. pp. 40. pdf-download
  • Gerd Wagner, Adrian Giurca, Sergey Lukichev, Grigoris Antoniou and Mikael Berndtsson. Strelka A Visual Rule Modeling Tool. REWERSE IST 506779 Report I1 D4. Apr-2006. pp. 23. Munchen, Germany. pdf-download
  • Gerd Wagner, Adrian Giurca, Sergey Lukichev, Grigoris Antoniou, Carlos Viegas Damasio and Norbert E. Fuchs. Language Improvements and Extensions. REWERSE IST 506779 Report I1 D8. Apr-2006. pp. 85. Munchen, Germany. pdf-download

2005

  • Anastasia Analyti, Grigoris Antoniou, Carlos Viegas Damasio and Gerd Wagner. In: Yolanda Gil, Enrico Motta, V. Richard Benjamins and Mark A. Musen (Eds.). Stable Model Theory for Extended RDF Ontologies. Proceedings of the 4th International Semantic Web Conference. Springer Verlag. 6 10 November-2005. volume 3729. pp. 21–36. Lecture Notes in Computer Science (LNCS). Galway, Ireland. pdf-download. digital identifier
  • Harold Boley, Mike Dean, Benjamin Grosof, Michael Kifer, Said Tabet and Gerd Wagner. RuleML Position Statement. Proceedings of W3C Workshop on Rule Languages for Interoperability. W3C. 27-28 April-2005. Washington, DC, USA. download
  • Harold Boley, Jing Mei, Michael Sintek and Gerd Wagner. RDF/RuleML Interoperability. Proceedings of W3C Workshop on Rule Languages for Interoperability. W3C. 27 28 April-2005. Washington, DC, USA. download
  • Adrian Giurca and Gerd Wagner. In: Asaf Adi, Suzette Stoutenburg and Said Tabet (Eds.). Towards an Abstract Syntax and Direct Model Theoretic Semantics for RuleML. Rules and Rule Markup Languages for the Semantic Web, First International Conference, RuleML 2005. Springer. 10 12 November-2005. volume 3791. pp. 45–55. Lecture Notes in Computer Science. Galway, Ireland. pdf-download. digital identifier
  • Said Tabet, Gerd Wagner, Silvie Spreeuwenberg, Paul D. Vincent, Gonzaques Jacques, Christian de Sainte Marie, Jon Pellant, Jim Frank and Jacques Durand. OMG Production Rule Representation Context and Current Status. Proceedings of W3C Workshop on Rule Languages for Interoperability. W3C. 27 28 April-2005. Washington, DC, USA. download
  • Gerd Wagner. In: Norbert Eisinger and Jan Maluszynski (Eds.). Rule Modeling and Markup. Tutorial Lectures of the First International Summer School Reasoning Web 2005. Springer. 25 29 July-2005. volume 3564. pp. 251–274. Lecture Notes in Computer Science. Msida, Malta. digital identifier
  • Gerd Wagner, Carlos Viegas Damasio and Grigoris Antoniou. Towards a General Web Rule Language. International Journal of Web Engineering and Technology. 2005. pp. 181 – 206. number: 2/3. pdf-download
  • Gerd Wagner, Adrian Giurca and Sergey Lukichev. In: F. Bry, F. Fages, M. Marchiori and H. Ohlbach (Eds.). A General Markup Framework for Integrity and Derivation Rules. Dagstuhl Seminar Proceedings 05371. 2005. Principles and Practices of Semantic Web Reasoning. pdf-download
  • Gerd Wagner, Adrian Giurca and Sergey Lukichev. In: Francois Bry, Francois Fages, Massimo Marchiori and Hans Juergen Ohlbach (Eds.). A General Markup Framework for Integrity and Derivation Rules. Principles and Practices of Semantic Web Reasoning. Internationales Begegnungs und Forschungszentrum fuer Informatik(IBFI), Schloss Dagstuhl, Germany. 2005. number: 05371. Dagstuhl Seminar Proceedings. Dagstuhl, Germany. pdf-download
  • Gerd Wagner and Kuldar Taveter. In: B. Henderson Sellers and P. Giorgini (Eds.). Towards Radical Agent Oriented Software Engineering Processes Based on AOR Modeling. Agent Oriented Methodologies. Idea Group Publishing. 2005. pp. 277–316
Technical reports
  • Anastasia Analyti, Grigoris Antoniou, Carlos Viegas Damasio and Gerd Wagner. Extended RDF as a Semantic Foundation of Rule Markup Languages. REWERSE IST 506779 Report I1 D3 2. Oct-2005. pdf-download
  • Gerd Wagner, Sergey Lukichev, Norbert E. Fuchs and Silvie Spreeuwenberg. First Version Controlled English Rule Language. REWERSE IST 506779 Report I1 D2. Feb-2005. pdf-download
  • Gerd Wagner, Giancarlo Viegas Damasio and Sergey Lukichev. First Version Rule Markup Languages. REWERSE IST 506779 Report I1 D3 1. Aug-2005. Munchen, Germany. pdf-download

2004

  • Anastasia Analyti, Grigoris Antoniou, Carlos Viegas Damasio and Gerd Wagner. Negation and Negative Information in the W3C Resource Description Framework. Annals of Mathematics, Computing and Teleinformatics. 2004. volume 1. pp. 25–34. number: 2. pdf-download. RDF, negation, partial logic
  • Grigoris Antoniou, Antonis Bikakis and Gerd Wagner. A Defeasible Logic Programming System for the Web. Proceedings of 16th IEEE International Conference on Tools with Artificial Intelligence (ICTAI 2004). IEEE Computer Society. 15 17 November-2004. pp. 756–757. Boca Raton, FL, USA. digital identifier
  • Grigoris Antoniou, Antonis Bikakis and Gerd Wagner. In: Grigoris Antoniou and Harold Boley (Eds.). A System for Nonmonotonic Rules on the Web. Proceedings of the Third International Workshop on Rules and Rule Markup Languages for the Semantic Web. Springer. 8 November-2004. volume 3323. pp. 23–36. Lecture Notes in Computer Science. Hiroshima, Japan. digital identifier
  • Giancarlo Guizzardi and Gerd Wagner. In: Paolo Bresciani, Paolo Giorgini, Brian Henderson Sellers, Graham Low and Michael Winikoff (Eds.). Towards Ontological Foundations for Agent Modeling Concepts Using the Unified Fundational Ontology (UFO). Revised Selected Papers of the 6th International Bi Conference Workshop on Agent Oriented Information Systems. Springer Verlag. 8 June-2004. volume 3508. pp. 110–124. Lecture Notes in Computer Science. Riga, Latvia. pdf-download. digital identifier
  • Giancarlo Guizzardi and Gerd Wagner. In: Janis Grundspenkis and Marite Kirikova (Eds.). A Unified Foundational Ontology and some Applications of it in Business Modeling. Proceedings of the CAiSE'04 Workshops. Faculty of Computer Science and Information Technology, Riga Technical University, Riga, Latvia. 7 11 June-2004. volume 3. pp. 129–143. Riga, Latvia. pdf-download
  • Giancarlo Guizzardi and Gerd Wagner. In: Janis Grundspenkis and Marite Kirikova (Eds.). On the ontological foundations of agent concepts. Proceedings of the CAiSE'04 Workshops in connection with The 16th Conference on Advanced Information Systems Engineering, Knowledgeand Model Driven Information Systems Engineering for Networked Organisations. Faculty of Computer Science and Information Technology, Riga Technical University, Riga, Latvia. 7 11 June-2004. volume 2. pp. 265–279. Riga, Latvia
  • Giancarlo Guizzardi, Gerd Wagner, Nicola Guarino and Marten van Sinderen. In: Anne Persson and Janis Stirna (Eds.). An Ontologically Well Founded Profile for UML Conceptual Models. Proceedings 16th International Conference on Advanced Information Systems Engineering CAiSE 2004. Springer Verlag. 7 11 June-2004. volume 3084. pp. 112–126. Lecture Notes in Computer Science. Riga, Latvia. pdf-download. digital identifier
  • Giancarlo Guizzardi, Gerd Wagner and Heinrich Herre. In: Enrico Motta, Nigel Shadbolt, Arthur Stutt and Nicholas Gibbins (Eds.). On the Foundations of UML as an Ontology Representation Language. Proceedings of 14th International Conference on Engineering Knowledgein the Age of the Semantic Web EKAW 2004. Springer. 5 8 October-2004. volume 3257. pp. 47–62. Lecture Notes in Computer Science. Whittlebury Hall, UK. pdf-download. digital identifier
  • Giancarlo Guizzardi, Gerd Wagner and Marten van Sinderen. In: Gregor Buchel, Bertin Klein and Thomas Roth Berghofer (Eds.). A Formal Theory of Conceptual Modeling Universals. Proceedings of the First International Workshop on Philosophy and Informatics WSPI '04. CEUR WS.org. 31 March-2004. volume 112. CEUR Workshop Proc.. Cologne, Germany. pdf-download
  • Jeroen van Luin, Florin Tulba and Gerd Wagner. Remodeling the Beer Game as an Agent Object Relationship Simulation. Proceedings of Workshop 2003: Agent Based Simulation 5. SCS European Publishing House. 3 5 May 2004-2004. pp. 5–10. Lisbon, Portugal. pdf-download
  • Gerd Wagner. In: P. Giorgini et al. (Eds.). Agent Oriented Information Systems. Springer Verlag. 2004. volume 3030. AOR Modelling and Simulation - Towards a General Architecture for Agent Based Discrete Event Simulation. pp. 174–188. LNAI. pdf-download
  • Gerd Wagner, Grigoris Antoniou, Said Tabet and Harold Boley. The Abstract Syntax of RuleML Towards a General Web Rule Language Framework. Proceedings of the IEEE/WIC/ACM International Conference on Web Intelligence(WI 2004). IEEE Computer Society. 20 24 September-2004. pp. 628–631. Beijing, China
Technical reports
  • Gerd Wagner, Silvie Spreeuwenberg, Grigoris Antoniou, Mikael Berndtsson and Kuldar Taveter. A First Version Visual Rule Language. REWERSE IST 506779 Report I1 D1. Feb-2004. pdf-download

2003

  • Gerd Wagner. A UML Profile for External Agent Object Relationship (AOR) Models. Agent Oriented Software Engineering III: Third International Workshop, AOSE 2002, Bologna, Italy, July 15, 2002. Revised Papers and Invited Contributions. Springer Berlin / Heidelberg. 2003. volume 2585. pp. 138–149. Lecture Notes in Computer Science (LNCS). pdf-download
  • Gerd Wagner. The Agent Object Relationship Meta Model: Towards a Unified View of State and Behavior. Information Systems. 2003. volume 28. pp. 475–504. number: 5. pdf-download
  • Gerd Wagner. Seven Golden Rules for a Web Rule Language. IEEE Intelligent Systems. Sep/Oct-2003. volume 18. number: 5. pdf-download
  • Gerd Wagner. In: F. Bry, N. Henze and J. Maluszynski (Eds.). Web Rules Need Two Kinds of Negation. Principles and Practice of Semantic Web Reasoning, Proceedings of the 1st International Workshop, PPSWR '03. Springer Verlag. 2003. volume 2901. pp. 33–50. Lecture Notes in Computer Science (LNCS). pdf-download

2001

  • Kuldar Taveter and Gerd Wagner. Agent Oriented Enterprise Modeling Based on Business Rules. Proc. of 20th Int. Conf. on Conceptual Modeling (ER2001). Springer Verlag. Nov-2001. volume 2224. pp. 527–540. LNCS. Yokohama, Japan. pdf-download

1999

  • Heinrich Herre, Jan O. M. Jaspars and Gerd Wagner. In: D.M. Gabbay and H. Wansing (Eds.). Partial Logics with Two Kinds of Negation as a Foundation for Knowledge Based Reasoning. What is Negation?. Kluwer Academic Publishers. 1999. pdf-download

1998

  • Gerd Wagner. Foundations of Knowledge Systems with Applications to Databases and Agents. Kluwer Academic Publishers. 1998. pdf-download

1991

  • Gerd Wagner. In: B. Talheim and H.D. Gerhardt (Eds.). A Database Needs Two Kinds of Negation. 3rd Symposium on Mathematical Fundamentals of Database and KnowledgeBase Systems. Springer Verlag. 1991. volume 495. pp. 357–371. Lecture Notes in Computer Science (LNCS)