M. Zahle, FRACTIONAL DIFFERENTIATION IN THE SELF-AFFINE CASE .5. THE LOCAL DEGREE OF DIFFERENTIABILITY, Mathematische Nachrichten, 185, 1997, pp. 279-306
Concepts of fractional differentiation are presented whose origins lie
in fractal geometry. The aim of the paper is to show their close rela
tionship to classical fractional calculus in the theory of function sp
aces.