Time: Tue 26 May 2026, at 15:10

Place: Room 314, The Second Teaching Building

Speaker: Nick Bezhanishvili, University of Amsterdam

This event is part of the Seminar Series on Frontier Issues in Logic.

Abstract:

In this talk, I will first review the Esakia and Jónsson–Tarski dualities for Heyting and modal algebras. I will then show how these dualities can be used to develop a theory of stable canonical formulas and rules, and how every superintuitionistic and modal logic can be axiomatized by such formulas and rules.

In the final part of the talk, I will present several applications of the method of stable canonical formulas and rules. In particular, I will explain how these methods yield an alternative and rather transparent geometric proof of the Blok–Esakia Theorem - one of the central results in superintuitionistic modal logics - stating that the lattice of superintuitionistic logics is isomorphic to the lattice of extensions of the modal logic Grz.