Seminar February 2nd

Monday, February 2th, 13:00, CRM Small Room

Speaker: Francesco Matucci, CRM

Title: Structure Theorems for Subgroups of Homeomorphisms Groups.

Abstract: We give a classification of the solvable subgroups G of the group Homeo_+(S^1) of all orientation-preserving homeomorphisms of the unit circle. The key tool is proving that the rotation number map is a group homomorphism and it is done by relating the dynamics of G and its group structure. Applications include new proofs of known results as the Margulis' theorem on the existence of a G-invariant probability measure on S^1 and Burslem-Wilkinson theorem on the classification of solvable groups of analytic diffeomorphisms (this is joint work with C. Bleak and M. Kassabov).

Seminar January 26th

Monday, January 26th, 13:00, CRM Small Room

Speaker: Bob Gilman, Stevens Institute of Technology

Title: Group Theoretical Questions from Cryptography

Abstract: The recent development of cryptosystems based on finitely presented groups has produced a number new questions in combinatorial group theory. We survey these questions and solve one of them.