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 such 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).