Characterization of multiplier spaces by wavelets and logarithmic Morrey spaces

In this paper, we consider multipliers from Sobolev spaces to Lebesgue spaces. We establish some wavelet characterization of multiplier spaces without using capacity. Further, we give a sharp logarithmic Morrey space condition for multipliers which lessens Fefferman's Morrey space condition to the logarithm level and generalizes Lemari,'s counter-example to non-integer cases and expresses his results in a more precise way. (C) 2012 Elsevier Ltd. All rights reserved.