A system for defeasible argumentation, with defeasible priorities

  • Henry Prakken
  • Giovanni Sartor
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1085)


Inspired by legal reasoning, this paper presents an argument-based system for defeasible reasoning, with a logic-programming-like language, and based on Dung's argumentation-theoretic approach to the semantics of logic programming. The language of the system has both weak and explicit negation, and conflicts between arguments are decided with the help of priorities on the rules. These priorities are not fixed, but are themselves defeasibly derived as conclusions within the system.


Logic Programming Legal Reasoning Argumentation Framework Default Logic Ground Instance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    A. Analyti and S. Pramanik, Reliable semantics for extended logic programs with rule prioritization. Journal of Logic and Computation 5 (1995), 303–324.Google Scholar
  2. 2.
    A. Bondarenko, F. Toni, R.A. Kowalski, An assumption-based framework for nonmonotonic reasoning. Proceedings of the Second International Workshop on Logic Programming and Nonmonotonic Reasoning, MIT Press, 1993, 171–89.Google Scholar
  3. 3.
    G. Brewka, Reasoning about priorities in default logic. Proceedings AAAI-94, 247–260.Google Scholar
  4. 4.
    G. Brewka, What does a defeasible rule base with explicit prioritiy information entail? Proceedings of the second Dutch/German Workshop on Nonmonotonic Reasoning, Utrecht 1995, 25–32.Google Scholar
  5. 5.
    P.M. Dung, On the acceptability of arguments and its fundamental role in nonmonotonic reasoning, logic programming, and n-person games. Artificial Intelligence 77 (1995), 321–357.CrossRefGoogle Scholar
  6. 6.
    P.M. Dung, An argumentation semantics for logic programming with explicit negation. Proceedings of the Tenth Logic Programming Conference, MIT Press 1993, 616–630.Google Scholar
  7. 7.
    H. Geffner and J. Pearl, Conditional entailment: bridging two approaches to default reasoning. Artificial Intelligence 53 (1992), 209–244.CrossRefMathSciNetGoogle Scholar
  8. 8.
    T.F. Gordon, The pleadings game: an exercise in computational dialectics. Artificial Intelligence and Law, Vol. 2, No. 4, 1994, 239–292.CrossRefGoogle Scholar
  9. 9.
    E. Laenens and D. Vermeir, A fixed points semantics for ordered logic. Journal of Logic and Computation Vol. 1 No. 2, 1990, 159–185.Google Scholar
  10. 10.
    R.P. Loui, J. Norman, J. Olson, A. Merrill, A design for reasoning with policies, precedents, and rationales. Proceedings of the Fourth International Conference on Artificial Intelligence and Law, ACM Press, 1993, 202–211.Google Scholar
  11. 11.
    D. Nute, Defeasible logic. In D. Gabbay (ed.) Handbook of Logic and Artificial Intelligence, Vol. 3. Oxford University Press, 1994, 353–395.Google Scholar
  12. 12.
    L.M. Pereira and J.J. Alferes, Well-founded semantics for logic programs with explicit negation. Proceedings ECAI-92.Google Scholar
  13. 13.
    J.L. Pollock, Defeasible reasoning. Cognitive Science 11 (1987), 481–518.CrossRefGoogle Scholar
  14. 14.
    H. Prakken, An argumentation framework in default logic. Annals of Mathematics and Artificial Intelligence, 9 (1993) 91–131.CrossRefGoogle Scholar
  15. 15.
    H. Prakken, A semantic view on reasoning about priorities (extended abstract) Proceedings of the Second Dutch/German Workshop on Nonmonotonic Reasoning, Utrecht 1995, 152–159.Google Scholar
  16. 16.
    H. Prakken and G. Sartor, On the relation between legal language and legal argument: assumptions, applicability and dynamic priorities. Proceedings of the Fifth International Conference on Artificial Intelligence and Law. ACM Press 1995, 1–9.Google Scholar
  17. 17.
    G.R. Simari and R.P. Loui, A mathematical treatment of defeasible argumentation and its implementation. Artificial Intelligence 53 (1992), 125–157.CrossRefGoogle Scholar
  18. 18.
    G. Vreeswijk, Studies in defeasible argumentation. Doctoral dissertation Free University Amsterdam, 1993.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • Henry Prakken
    • 1
  • Giovanni Sartor
    • 2
    • 3
  1. 1.Computer/Law InstituteFree UniversityAmsterdam
  2. 2.CIRFIDUniversity of BolognaBologna
  3. 3.IDG-CNRFirenze

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