On Warranted Inference in Possibilistic Defeasible Logic Programming

Possibilistic Defeasible Logic Programming (P DeLP) is a logic pro gramming language which combines features from argumentation theory and logic programming incorporating as well the treatment of possibilistic uncertainty and fuzzy knowledge at object language level Defeasible argumentation in general and P DeLP in particular provide a way of modelling non monotonic inference From a logical viewpoint capturing defeasible inference relationships for modelling argument and warrant is particularly important as well as the study of their logical properties This paper analyzes a non monotonic operator for P DeLP which models the expansion of a given program P by adding new weighed facts associated with warranted literals Different logical properties are studied and contrasted with a traditional SLD based Horn logic providing useful comparison criteria that can be extended and applied to other argumentation frameworks