Logic Seminar

Speaker: Wesley Calvert, Southern Illinois University

http://math.siu.edu/faculty-staff/faculty/calvert.php

Title: Strong jump inversion for structures

Abstract: Consider the set of Turing degrees in which a fixed structure A has an isomorphic copy. For some classes of structures (such as Boolean algebras), there is a “forbidden region” for the least elements of this set: if there is a low copy, there must also be a computable copy. For other classes of structures, any spectrum is possible. Characterizing structures with this forbidden region seems difficult and is so far unsolved. The present talk will present a partial solution.