Decompositions of Gelfand-Shilov kernels into kernels of similar class
  We prove that any linear operator with kernel in a Gelfand-Shilov space is a composition of two operators with kernels in the same Gelfand-Shilov space. We also give links on numerical approximations for such compositions. We apply these composition rules to establish Schatten-von Neumann properties for such operators. 
Joachim Toft, Andrei Khrennikov, B\"orje Nilsson, Sven Nordebo
math.FA math.OA