Density results for the modular group of infinite-type surfaces

Abstract

In this work we show two results about approximating, with respect to the compact-open topology, mapping classes on surfaces of infinite-type by quasi-conformal maps, in particular we are interested in density results. The first result is that given any infinite-type surface $S$ there exists a hyperbolic structure $X$ on $S$ such that $\text{PMCG}(S)\subseteq \overline{\text{Mod}(X)}$, for $\text{Mod}(X)$ the set of quasi-conformal homeomorphism on $X$. The second result is that given any surface $S$ with countably many ends then there exists a hyperbolic structure $X$ such that $\text{MCG}(S)=\overline{\text{Mod}(X)}$.