Approximation property and nuclearity on mixed-norm , modulation and Wiener amalgam spaces
arXiv:1410.4687
Abstract
In this paper we first prove the metric approximation property for weighted mixed-norm spaces. Using Gabor frame representation this implies that the same property holds in weighted modulation and Wiener amalgam spaces. As a consequence, Grothendieck's theory becomes applicable, and we give criteria for nuclearity and -nuclearity for operators acting on these space as well as derive the corresponding trace formulae. Finally, we apply the notion of nuclearity to functions of the harmonic oscillator on modulation spaces.
22 pages; slightly updated final version, to appear in J. Lond. Math. Soc