On the genericity of loxodromic actions

Abstract

One way of picking a "generic" element of a finitely generated group is to pick a random element with uniform probability in a large ball centered on $1$ in the Cayley graph. If the group acts on a $\delta$-hyperbolic space, with at least one element acting loxodromically, then it is plausible that generic elements should act loxodromically with high probability. In this paper we prove that the probability of acting loxodromically is bounded away from 0, provided the group satisfies a very weak automaticity condition, and provided a certain compatibility condition linking the automatic with the $\delta$-hyperbolic structure is satisfied. We present several applications of this result, including the genericity of pseudo-Anosov braids.

arXiv comment23 pages, 1 figure. Exposition improved, small errors corrected, added example of hyperbolic groups acting on their Cayley graphs