Genericity of ergodicity for Sobolev homeomorphisms

In this paper we obtain a weak version of Lusin’s theorem in the Sobolev-$(1,p)$ uniform closure of volume preserving Lipschitz homeomorphisms on closed and connected $d$-dimensional manifolds, $d\ge 2$ and $0<p<1$. With this result at hand we will be able to prove that the ergodic elements are generic. This establishes a version of Oxtoby and Ulam theorem for this Sobolev class. We also prove that, for $1\le p<d-1$, the topological transitive maps are generic.