Series: Penn State Logic Seminar Date: Tuesday, January 25, 2005 Time: 2:30 - 3:45 PM Place: 103 Pond Laboratory Speaker: John Clemens, Penn State, Mathematics Title: Extending Partial Automorphisms of Finite Structures Abstract: A question that has occurred in several contexts is to determine when a finite structure A can be extended to a finite structure B so that every partial automorphism of A extends to a (full) automorphism of B. Hrushovski showed that this is true for graphs. Recently, Vershik and Solecki (independently) showed that the analogous property holds for metric spaces. I will present Solecki's proof of this result, which uses a theorem of Herwig and Lascar (which I will not prove).