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商空间的k-端点和k-严格凸性
引用本文:王宏志,段丽芬,崔云安.商空间的k-端点和k-严格凸性[J].河南师范大学学报(自然科学版),2008,36(4).
作者姓名:王宏志  段丽芬  崔云安
作者单位:1. 通化师范学院,数学系,吉林,通化134002
2. 哈尔滨理工大学,应用科学学院,哈尔滨,150080
摘    要:证明了商空间X/M单位球面上的点x]为闭单位球的k-端点的充分条件是x]与X的单位球面的交集中任一点均为闭单位球的k-端点,其中M是Banach空间X的可逼近子空间.进而推出了Banach空间X以它的可逼近子空间M为模的商空间X/M对X的k-严格凸性的继承性.同时,以由N-函数生成的Orlicz空间为例,说明了上述结论成立可逼近条件是必要的.

关 键 词:商空间  k-端点  k-严格凸  可逼近

On the Extreme Point and Rotundity of Quotient Spaces
WANG Hong-zhi,DUAN Li-fen,CUI Yun-an.On the Extreme Point and Rotundity of Quotient Spaces[J].Journal of Henan Normal University(Natural Science),2008,36(4).
Authors:WANG Hong-zhi  DUAN Li-fen  CUI Yun-an
Abstract:This paper presents that a point in the unit sphere of X/M is k-extreme point of closed unit ball if every point on x]∩S(X) is a k-extreme point of closed unit ball.Here M is subpace of Banach space X and it is proximal in X.And by it,k-rotundity of X may be lifted to the quotient space X/M if X is proximal in X.Moreover,taking the example of Orlicz space generalized N-function,it points out that the condition making the above conclusion tenable is essential in general.
Keywords:quotient space  k-extreme point  k-rotundity  approximatibility
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