TIME: 1:30 -- 2:20 pm, Tuesday, April 7, 2009 PLACE: CSE 503 SPEAKER: Yuri Gurevich, Microsoft Research TITLE: Proof of Church's Thesis ABSTRACT: Church's Thesis asserts that every effectively calculable numerical function is recursive. Why we believe the thesis? Careful analysis shows that existing argumentation is insufficient. Kurt Goedel surmised that "it might be possible ... to state axioms which embody the generally accepted properties of [effective calculability], and to do something [to prove the thesis] on that basis". That is exactly what we have done. This is joint work with Nachum Dershowitz of Tel Aviv University