A Fixed-Point Semantics for Plausible Logic

Abstract

Plausible Logic is a non-monotonic logic with an efficient implementation, but no semantics. This paper gives Plausible Logic a fixed-point semantics, similar to the extensions of Reiter's Default Logic. The proof theory is sound but deliberately incomplete with respect to this semantics. This is because the semantics is an attempt to define what follows from a plausible theory, rather than merely giving a different characterisation of what is provable.