Actions of solvable Baumslag-Solitar groups on surfaces with (pseudo-)Anosov elements

Juan Alonso, Nancy Guelman, Juliana Xavier

Published 2013-10-09, updated 2014-05-26Version 3

Let $BS(1,n)= <a,b : a b a ^{-1} = b ^n>$ be the solvable Baumslag-Solitar group, where $n \geq 2$. We study representations of $BS(1, n)$ by homeomorphisms of closed surfaces with (pseudo-)Anosov elements. That is, we consider a closed surface $S$, and homeomorphisms $f, h: S \to S$ such that $h f h^{-1} = f^n$, for some $ n\geq 2$. It is known that $f$ (or some power of $f$) must be homotopic to the identity. Suppose that $h$ is pseudo-Anosov with stretch factor $\lambda >1$. We show that $<f,h>$ is not a faithful representation of $BS(1, n)$ if $\lambda > n$. Moreover, we show that there are no faithful representations of $BS(1, n)$ by torus homeomorphisms with $h$ an Anosov map and $f$ area preserving (regardless of the value of $\lambda$).