A Simple Proof of Kwapien's Theorem

Abstract

The purpose of the present note is to prove in a self-contained way Kwapien's theorem that gives a criterion for Hilbertizability of normed spaces. Original proof [1], [2] has required much more complicated discussions. Many authors have investigated [3, 6] relating problems, but their researches are based on mutual quotations, thus it is difficult to follow their studies for readers not so familiar in the topic. So the author believes that a self-contained proof has some meaning.