Citkin's characterization of hereditarily structurally complete intermediate logics via Esakia duality

Nick Bezhanishvili

(Joint work with Tommaso Moraschini)

Citkin (1978) gave an interesting characterization of hereditarily structurally complete (HSC) varieties of Heyting algebras: a variety of Heyting algebras is HSC if and only if it omits five special finite algebras. In this talk, I will give an alternative proof of Citkin's result using Esakia duality and universal models.