哥氏空間之準補餘子空間

Abstract

Let Z be a quasi-complemented subspace of a Grothendieck space X with quasi-complement Ysuch that the unit ball of Z* is weak*-sequentially compact, then Z is quasi-complemented in X** and Y**/Y is isomorphic to X**/X. If a Grothendieck space has a fundamental biorthogonal system, then it possesses a aeperable quasi-complemented subspace.