Teresa Alsinet

Publications (42) View all

• Article: On the Semantics and Automated Deduction for PLFC, a Logic of Possibilistic Uncertainty and Fuzziness

  Teresa Alsinet, Lluis Godo, Sandra Sandri
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  ABSTRACT: Possibilistic logic is a well-known graded logic of uncertainty suitable to reason under incomplete information and partially inconsistent knowledge, which is built upon classical first order logic. There exists for Possibilistic logic a proof procedure based on a refutation complete resolution-style calculus. Recently, a syntactical extension of first order Possibilistic logic (called PLFC) dealing with fuzzy constants and fuzzily restricted quantifiers has been proposed. Our aim is to present steps towards both the formalization of PLFC itself and an automated deduction system for it by (i) providing a formal semantics; (ii) defining a sound resolution-style calculus by refutation; and (iii) describing a first-order proof procedure for PLFC clauses based on (ii) and on a novel notion of most general substitution of two literals in a resolution step. In contrast to standard Possibilistic logic semantics, truth-evaluation of formulas with fuzzy constants are many-valued instead of boolean, and consequently an extended notion of possibilistic uncertainty is also needed.
  01/2013;
• Article: A Complete Calculus for Possibilistic Logic Programming with Fuzzy Propositional Variables

  Teresa Alsinet, Lluis Godo
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  ABSTRACT: In this paper we present a propositional logic programming language for reasoning under possibilistic uncertainty and representing vague knowledge. Formulas are represented by pairs (A, c), where A is a many-valued proposition and c is value in the unit interval [0,1] which denotes a lower bound on the belief on A in terms of necessity measures. Belief states are modeled by possibility distributions on the set of all many-valued interpretations. In this framework, (i) we define a syntax and a semantics of the general underlying uncertainty logic; (ii) we provide a modus ponens-style calculus for a sublanguage of Horn-rules and we prove that it is complete for determining the maximum degree of possibilistic belief with which a fuzzy propositional variable can be entailed from a set of formulas; and finally, (iii) we show how the computation of a partial matching between fuzzy propositional variables, in terms of necessity measures for fuzzy sets, can be included in our logic programming system.
  01/2013;
• Article: A Logic Programming Framework for Possibilistic Argumentation with Vague Knowledge

  Carlos Chesnevar, Guillermo Simari, Teresa Alsinet, Lluis Godo
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  ABSTRACT: Defeasible argumentation frameworks have evolved to become a sound setting to formalize commonsense, qualitative reasoning from incomplete and potentially inconsistent knowledge. Defeasible Logic Programming (DeLP) is a defeasible argumentation formalism based on an extension of logic programming. Although DeLP has been successfully integrated in a number of different real-world applications, DeLP cannot deal with explicit uncertainty, nor with vague knowledge, as defeasibility is directly encoded in the object language. This paper introduces P-DeLP, a new logic programming language that extends original DeLP capabilities for qualitative reasoning by incorporating the treatment of possibilistic uncertainty and fuzzy knowledge. Such features will be formalized on the basis of PGL, a possibilistic logic based on Godel fuzzy logic.
  07/2012;
• Conference Proceeding: Maximal Ideal Recursive Semantics for Defeasible Argumentation.

  Teresa Alsinet, Ramón Béjar, Lluis Godo, Francesc Guitart
  Scalable Uncertainty Management - 5th International Conference, SUM 2011, Dayton, OH, USA, October 10-13, 2011. Proceedings; 01/2011
• Source

  Available from: Ramón Béjar

  Chapter: A Computational Method for Defeasible Argumentation Based on a Recursive Warrant Semantics

  Teresa Alsinet, Ramón Béjar, Lluís Godo
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  ABSTRACT: In a recent paper[2] the authors have formalized a recursive semantics for warranted conclusions in a general defeasible argumentation framework based on a propositional logic. The warrant recursive semantics is based on a general notion of collective (non-binary) conflict among arguments allowing to ensure direct and indirect consistency properties. This general framework has also been extended with levels of defeasibility and with a level-wise recursive definition of warranted and blocked conclusions. In this paper we focus on the recursive semantics for the particular framework of Defeasible Logic Programming (DeLP) extended with levels of defeasibility, called RP-DeLP, for which we characterize programs with a unique output (extension) for warranted conclusions, and we design, for this type of programs, an algorithm for computing warranted conclusions in polynomial space and with an upper bound on complexity equal to P NP . Keywordsdefeasible argumentation-recursive semantics-computational aspects
  11/2010: pages 40-49;