|zpravodaj ČSKI - únor 2019 |
datum: 20.2.2019 v 16:00
název: Uniform interpolation for IPC via an open mapping theorem for Esakia spaces
přednášející: Luca Reggio (UI)
místo konání: UI, 2.patro, místnost č.318
souhrn: The uniform interpolation property of the intuitionistic propositional calculus (IPC) was first proved by Pitts in 1992 by means of proof-theoretic methods. We prove an open mapping theorem for the topological spaces dual to finitely presented Heyting algebras. In turn, this yields a short, self-contained semantic proof of Pitts result. Our proof is based on the methods of Ghilardi & Zawadowski. However, it does not require sheaves nor games, only basic duality theory for Heyting algebras. This is joint work with Sam van Gool.