Sobolev homeomorphisms and composition operators on homogeneous Lie groups

In this article we study Sobolev homeomorphisms and composition operators on homogeneous Lie groups. We prove, that a measurable homeomorphism $\varphi: \Omega \to\widetilde{\Omega}$ belongs to the Sobolev space $L^{1}_{q}(\Omega; \widetilde{\Omega})$, $1\leq q < \infty$, if and only if $\varphi$ generates a bounded composition operator on Sobolev spaces.