Stratified least fixpoint logic

Abstract

Stratified least fixpoint logic, or SLFP, characterizes the expressibility of stratified logic programs and, in a different formulation, has been used as a logic of imperative programs. These two formulations of SLFP are proved to be equivalent. A complete sequent calculus with one infinitary rule is given for SLFP. It is argued that SLFP is the most appropriate assertion language for program verification. In particular, it is shown that traditional approaches using first-order logic as an assertion language only restrict to interpretations where first-order logic has the same expressibility as SLFP.