Generalized lipschitz conditions and riesz derivatives on the space of bessel potentials L^p_α

Abstract

In the foregoing Note (this Journal Vol.I.p. 75-99) the space of n-dimensional Bessel potentials L^p _x was deseribed in terms of generalized Lipschitz conditions of f or its Riesz transform for 0<∝≦2 The still open case ∝>1 is treated in the first half of this paper, firstly by introducing appropriate iterates of the cited conditions, secondly by using derivatives of f and its Riesz transform, in particular the Laplacian △ and the gradient of the Riesz transformation(▽,R and by applying the former results In Section 6 a definition of a Riesz derivative of order ∝ is given and based upon the concept: Integrate f(m-α)-times in the sense of Riesz and then differentiate [d]m-times (by considering the limit of suitable difference quotients of f). Necessary and sufficient conditions for the existence of these Riesz derivatives are obtained All results also hold in the non-reflexive spaces[d]