Homeomorphism of S^1 and Factorization

Doug Pickrell

Published 2014-08-23Version 1

For each $n > 0$ there is a one complex parameter family of homeomorphisms of the circle consisting of linear fractional transformations `conjugated by $z \to z^n$'. We show that these families are free of relations, which determines the structure of `the group of homeomorphisms of finite type'. We also discuss a number of questions regarding factorization for more robust groups of homeomorphisms of the circle in terms of these basic building blocks, and the correspondence between smoothness properties of the homeomorphisms and decay properties of the parameters.