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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 2010 Volume 87, Issue 3, Pages 396–401 (Mi mzm4177)

This article is cited in 7 papers

Degree of Discrete Generation of Compact Sets

A. V. Ivanova, E. V. Osipovb

a Petrozavodsk State University, Faculty of Mathematics
b M. V. Lomonosov Moscow State University

Abstract: In the present paper, under the continuum hypothesis, we construct an example of a discretely generated compact set $X$ whose square is not discretely generated. For each compact set $X$, there is an ordinally valued characteristic $\operatorname{idc}(X)$, which is the least number of iterations of the $d$-closure generating, as a result, the closure of any original subset $X$. We prove that if $\chi(X)\le\omega_\alpha$, then $\operatorname{idc}(X)\le\alpha+1$.

Keywords: discretely generated compact set, compact Hausdorff space, $d$-closure, compact extension, one-point compactification, continuum hypothesis.

UDC: 515.12

Received: 14.03.2007
Revised: 07.04.2009

DOI: 10.4213/mzm4177


 English version:
Mathematical Notes, 2010, 87:3, 367–371

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