A Bourgain-Brezis-Mironescu characterization of higher order   Besov-Nikol'skii spaces
  We study a class of nonlocal functionals in the spirit of the recent characterization of the Sobolev spaces $W^{1,p}$ derived by Bourgain, Brezis and Mironescu. We show that it provides a common roof to the description of the $BV(\mathbb{R}^N)$, $W^{1,p}(\mathbb{R}^N)$, $B_{p,\infty}^s(\mathbb{R}^N)$ and $C^{0,1}(\mathbb{R}^N)$ scales and we obtain new equivalent characterizations for these spaces. We also establish a non-compactness result for sequences and new (non-)limiting embeddings between Lipschitz and Besov spaces which extend the previous known results. 
Julien Brasseur
math.FA