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).