Hitchhiker's guide to the fractional Sobolev spaces
AbstractThis paper deals with the fractional Sobolev spaces Ws,p. We analyze the relations among some of their possible definitions and their role in the trace theory. We prove continuous and compact embeddings, investigating the problem of the extension domains and other regularity results.Most of the results we present here are probably well known to the experts, but we believe that our proofs are original and we do not make use of any interpolation techniques nor pass through the theory of Besov spaces. We also present some counterexamples in non-Lipschitz domains.
s, p-Harmonic Approximation of Functions of Least W s,l-Seminorm
Abstract We investigate the convergence as $p\searrow 1$ of the minimizers of the $W^{s,p}$-energy for $s\in (0,1)$ and $p\in (1,\infty )$ to those of the $W^{s,1}$-energy, both in the pointwise sense and by means of $\Gamma $-convergence. We also address the convergence of the corresponding Euler–Lagrange equations and the equivalence between minimizers and weak solutions. As ancillary results, we study some regularity issues regarding minimizers of the $W^{s,1}$-energy.