Mapping theorems on א-spaces

نویسنده

  • Masami Sakai
چکیده

In this paper we improve some mapping theorems on א-spaces. For instance we show that an א-space is preserved by a closed and countably bi-quotient map. This is an improvement of Yun Ziqiu’s theorem: an א-space is preserved by a closed and open map.

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تاریخ انتشار 2010