Continuing the study of the linear topological characterizatian of inner product spaces initiated by J.S. Cohen and S. Kwapien
we find out a class of Banach spaces denoted by ∑
which contains all Hilbert spaces as it's one part of all elements.every one element in ∑ can be use to instead for the instation of l2 which in [2]. And we pull S. Kwapien's result foreward in general and easy to use.