On the regularity of the composition of diffeomorphisms
  For $M$ being a closed manifold or the Euclidean space we present a detailed proof of regularity properties of the composition of $H^s$-regular diffeomorphisms of $M$ for $s > 1/2\dim M + 1$. 
Hasan Inci, Thomas Kappeler, and Peter Topalov
math.AP