Asymptotic behavior of extremals for fractional Sobolev inequalities associated with singular problems.

Abstract

Let be a smooth, bounded domain of RN , ω be a positive, L1-normalized function, and 0 < s < 1 < p. We study the asymptotic behavior, as p → ∞, of the pair p p, u p, where p is the best constant C in the Sobolev-type inequality C exp (log |u| p)ωdx ≤ [u] p s,p ∀ u ∈ Ws,p 0 () and u p is the positive, suitably normalized extremal function corresponding to p. We show that the limit pairs are closely related to the problem of minimizing the quotient |u|s / exp (log |u|)ωdx , where |u|s denotes the s-Hölder seminorm of a function u ∈ C0,s 0 ().