| Monday 13 January 2025 | |
| Events for day: Thursday 26 December 2024 |
| 14:00 - 16:00 Mathematical Logic Weekly Seminar Normal Subgroups in the Automorphism Group of Models of Peano Arithmetic School MATHEMATICS It is well-known that the family of automorphisms of any structure constitutes a topological group. In the late 1980s and 1990s, significant progress was made in the understanding of the automorphism group of models of Peano arithmetic (PA). In particular, Richard Kaye provided a landmark characterization of the closed normal subgroups of the automorphism group of a countable recursively saturated model M of PA. His work established an infinite Galois-like correspondence between these closed normal subgroups and invariant initial segments of M. He also conjectured the existence of another correspondence between the non-closed normal subgroups ... |