Some remarks on a formula for Sobolev norms due to Brezis, Van Schaftingen and Yung

Arkady Poliakovsky

We provide answers to some questions raised in a recent work by H. Brezis, J. Van Schaftingen and Po-Lam Yung concerning the Gagliardo semi-norm $|u{|}_{W^{s,q}}$ computed at $s=1$…