Factorizations for quasi-Banach time-frequency spaces and Schatten classes

Abstract

We deduce factorization properties for a quasi-Banach module over a quasi-Banach algebra. Especially we extend a result by Hewitt and prove that if any such algebra which possess a bounded left approximate identity, then any element in the module can be factorized. As applications, we deduce factorization properties for Wiener amalgam spaces, for an extended family of modulation spaces and for Schatten symbol classes in pseudo-differential calculus under multiplications like convolutions, twisted convolutions and symbolic products. For example we show for Wiener amalgam spaces that WL^{1,r}*WL^{p,q}=WL^{p,q} when r in (0,1], and p and q are finite and larger than r. In particular we improve Rudin's identity L^1*L^1=L^1.

46 pages. This is the third version. We discovered that one of earlier main result, factorization of general quasi-Banach algebras and modules was a special case of another published result. The paper is now focused on applications. Because of fundamental changes, the different arXiv versions have different titles