A Global Compactness type result for Palais-Smale sequences in fractional Sobolev spaces

We extend the Global Compactness result by M. Struwe (Math. Z, 1984) to any fractional Sobolev spaces ${\dot{H}}^s(\mathrm{\Omega })$ for $0<s<N\mathrm{/}2$ and $\Omega \subset $\mathbb{R}$^N$ a bounded domain with smooth boundary. The proof is a simple direct consequence of the so-called Profile Decomposition of P. Gerard (ESAIM: Control, Optimisation and Calculus of Variations, 1998).