Translational Embeddings via Stable Canonical Rules

Abstract

This paper presents a new uniform method for studying modal companions of superintuitionistic deductive systems and related notions, based on the machinery of stable canonical rules. Using our method, we obtain an alternative proof of the Blok-Esakia theorem both for logics and for rule systems, and prove an analogue of the Dummett-Lemmon conjecture for rule systems. Since stable canonical rules may be developed for any rule system admitting filtration, our method generalises smoothly to richer signatures. We illustrate this by applying our techniques to prove analogues of the Blok-Esakia theorem (for both logics and rule systems) and of the Dummett-Lemmon conjecture (for rule systems) in the setting of tense companions of bi-superintuitionistic deductive systems. We also use our techniques to prove that the lattice of rule systems (logics) extending the modal intuitionistic logic KM and the lattice of rule systems (logics) extending the provability logic GL are isomorphic.