Nonmonotonic logics are usually characterized by the presence of some notion of `conditional' that fails monotonicity. Research on nonmonotonic logics is therefore largely concerned with the defeasibility of argument forms and the associated normality (or abnormality) of its constituents. In contrast, defeasible modes of inference aim to formalize the defeasible aspects of modal notions such as actions, obligations and knowledge. In this work we enrich the standard possible worlds semantics with a preference ordering on worlds in Kripke models. The resulting family of modal logics allow for the elegant expression of defeasible modalities. We also propose a tableau calculus which is sound and complete with respect to our preferential semantics.
Reference:
Britz, K and Varzinczak, I. 2013. Defeasible modalities. In: Fourteenth conference on Theoretical Aspects of Rationality and Knowledge (TARK), Chennai, India, 7-9 January 2013
Britz, K., & Varzinczak, I. (2013). Defeasible modalities. Centre for Artificial Intelligence Research. http://hdl.handle.net/10204/6801
Britz, K, and I Varzinczak. "Defeasible modalities." (2013): http://hdl.handle.net/10204/6801
Britz K, Varzinczak I, Defeasible modalities; Centre for Artificial Intelligence Research; 2013. http://hdl.handle.net/10204/6801 .
Fourteenth conference on Theoretical Aspects of Rationality and Knowledge (TARK), Chennai, India, 7-9 January 2013. Published in Centre for Artificial Intelligence Research