The Gabor Frames And Littlewood Problem

A basic question in Gabor analysis is how to classify all the triples (g, a, b) such that g generates a Gabor frame with respects to the paramenters a and b. By solving the equivalent Littlewood problem we character (?) for which ((?), 1, 1) is a frame,We study the case of ((?),1, 1) and will get some characterization when k≥5.The cases we study read as follows:(1) When k = 5 ,we get sufficient condition of non-Gabor frame for some((?),1, 1).(2) When k > 5 we get sufficient condition of non-Gabor frame forsome ((?),1, 1)...