研究了Banach空间X中的有界闭凸集C的弱紧性与其可逼近性的关系,证明了C是弱紧的当且仅当C在每个包含它(在仿射等距的意义下)的Banach空间中均是可逼近的.而当C不是完全时,C是弱紧的当且仅当对于x的每个等价范数|·|,C在(X,|·|)中均是可逼近的.
We investigate the relationship between the weakly compactness and the proximinality of a bounded closed convex set C in a Banach space X. We prove that C is weakly compact if and only if C is proximinal in every Banach space which contains it (in the sense of affine isometry). And when C is not total,we show that C is weakly compact if and only if for every equivalent norm |·| on X,C is proximinal in (X, |·| ).