Tangent Cones in Besov Spaces
Résumé
Tangent cones for obstacle problem arise when studying differentiability of metric projection. Characterising the tangent cones is the first step in these considerations. This has been done in some of the Sobolev spaces using Hilbert space methods. In this article we describe these tangent cones precisely, using non--linear potential theoretic ideas, for all Besov spaces $B_\alpha^p,q$, $1