Fuzzy Autoepistemic Logic: Reflecting about Knowledge of Truth Degrees

Autoepistemic logic is one of the principal formalisms for nonmonotonic reasoning. It extends propositional logic by offering the ability to reason about an agent’s (lack of) knowledge or beliefs. Moreover, it is well known to generalize the stable model semantics of answer set programming. Fuzzy logics on the other hand are multi-valued logics, which allow to model the intensity with which a property is satisfied. We combine these ideas to a fuzzy autoepistemic logic which can be used to reason about one’s knowledge about the degrees to which proporties are satisfied. In this paper we show that many properties from classical autoepistemic logic remain valid under this generalization and that the important relation between autoepistemic logic and answer set programming is preserved in the sense that fuzzy autoepistemic logic generalizes fuzzy answer set programming.