Dynamics of Convex Cocompact Subgroups of Mapping Class Groups
  For a convex cocompact subgroup $G<Mod(S)$, and points $x,y \in Teich(S)$ we obtain asymptotic formulas as $R\to \infty$ of $|B_{R}(x)\cap Gy|$ as well as the number of conjugacy classes of pseudo-Anosov elements in $G$ of dilatation at most $R$. We do this by developing an analogue of Patterson-Sullivan theory for the action of $G$ on $PMF$. 
Ilya Gekhtman
math.DS math.DG