D. Massart, STABLE NORMS OF SURFACES - LOCAL-STRUCTURE OF THE UNIT BALL AT RATIONAL DIRECTIONS, Geometric and functional analysis, 7(6), 1997, pp. 996-1010
Let (M, g) be a closed orientable surface, equipped with a smooth Fins
ler metric. The metric induces a norm on the real homology of M, calle
d a stable norm. We show this norm is neither strictly convex, nor smo
oth.