Formalizing Simultaneous Critical Pairs for Confluence of Left-Linear Rewrite Systems

Abstract

We report on the formalization of a sufficient condition for confluence of first-order left-linear rewrite systems within the proof assistant Isabelle/HOL. This criterion, originally proposed by Okui (1998), is based on simultaneous critical pairs, which finitely represent peaks consisting of a multi-step and a normal step. It properly subsumes the formalized result on development-closed critical pairs.