Preferential defeasibility: utility in defeasible logic programming

The development of Logic Programming and Defeasible Argumentation lead to Defeasible Logic Programming. Its core resides in the characterization of the warrant procedure. Defeasible Argumentation has provided a solid foundation over which the standard formalization of this procedure has been constructed. A key element in the warrant procedure is the criterion according to which two contradicting arguments are compared and eventually one of them deemed as defeating the other. The purely syntactic Specificity criterion has constituted the main choice in the design of the warrant procedure. Nevertheless, it seems unreasonable to limit the possibilities of comparison among arguments only to syntactic criteria. The justification of the methods of Defeasible Argumentation are largely pragmatic. Therefore, it seems sensible to expand the set of comparison criteria to incorporate other pragmatic reasons for choosing one argument over another. Decision Theory is the natural choice to model decision-makers. Clearly, as a discipline, it has characterized and introduced formal models in all kinds of pragmatic criteria used in actual choice situations. Here, we will present the framework of Preferential Defeasible Logic Programming. This framework extends the original comparison criteria of specificity redefining it by allowing different preferential values for activation sets. This extension leads to interesting results where the decision is taken considering not only specificity, but also the corresponding pragmatic relation of preferences.

Authors

• Fernando A. Tohmé
• Guillermo Ricardo Simari

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