2003年4月
Selections and sandwich-like properties via semi-continuous Banach-valued functions
JOURNAL OF THE MATHEMATICAL SOCIETY OF JAPAN
- ,
- ,
- 巻
- 55
- 号
- 2
- 開始ページ
- 499
- 終了ページ
- 521
- 記述言語
- 英語
- 掲載種別
- DOI
- 10.2969/jmsj/1191419128
- 出版者・発行元
- MATH SOC JAPAN
We introduce lower and upper semi-continuity of a map to the Banach space c(0)(lambda) for an infinite cardinal lambda. We prove that the following conditions (i), (ii) and (iii) on a T-1-space X are equivalent: (i) For every two maps g, h : X --> c(0)(lambda) such that g is upper semi-continuous, h is lower semi-continuous and g less than or equal to h, there exists a continuous map f : X --> c(0)(lambda), with g less than or equal to f less than or equal to h. (ii) For every Banach space Y, with w(Y) less than or equal to lambda, every lower semi-continuous set-valued mapping phi : X --> C-c(Y) admits a continuous selection, where C-c(Y) is the set of all non-empty compact convex sets in Y. (iii) X is normal and every locally finite family F of subsets of X with \F\ < lambda, has a locally finite Open expansion provided it has a point-finite open expansion. We also characterize several paracompact-like properties by inserting continuous maps between semi-continuous Banach-valued functions.
- リンク情報
- ID情報
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- DOI : 10.2969/jmsj/1191419128
- ISSN : 0025-5645
- Web of Science ID : WOS:000182748500011