Time:  12  1:20 p.m. 
Room: 
DH 1209

Speaker: 
Kohei Kishida Doctoral candidate Department of Philosophy University of Pittsburgh 
Title: 
Topological Semantics for Modal Logic

Abstract:  As Tarski showed, the Stone representation theorem for Boolean algebras extends to algebras with operators to give topological semantics for (classical) propositional modal logic, in which the ``necessity'' operation is modeled by taking the interior of an arbitrary subset of a topological space. This talk will show how to extend this interpretation from propositional to firstorder logic by using the topos of all sheaves on a space, or its equivalent notion of local homeomorphisms. 