19.8LOApr 13
Duality for Constructive Modal Logics: from Sahqlvist to Goldblatt-ThomasonJim de Groot, Ian Shillito, Ranald Clouston
We carry out a semantic study of the constructive modal logic CK. We provide a categorical duality linking the algebraic and birelational semantics of the logic. We then use this to prove Sahlqvist style correspondence and completeness results, as well as a Goldblatt-Thomason style theorem on definability of classes of frames.