[KSCI] Korea Science Citation Index Service

http://dx.doi.org/10.4134/CKMS.2011.26.2.297

A NOTE ON SPACES WHICH HAVE COUNTABLE TIGHTNESS

Hong, Woo-Chorl (Department of Mathematics Education Pusan National University)

Publication Information

Communications of the Korean Mathematical Society / v.26, no.2, 2011 , pp. 297-304 More about this Journal

Abstract

In this paper, we introduce closure operators [ ${\cdot}$ ]c and [ ${\cdot}$ ]a on a space and study some relations among [ ${\cdot}$ ]c, [ ${\cdot}$ ]a and countable tightness. We introduce the concepts of a strongly sequentially closed set and a strongly sequentially open set and show that a space X has countable tightness if and only if every strongly sequentially closed set is closed if and only if every strongly sequentially open set is open. Finally we find a generalization of the weak Fr $$\$ chet-Urysohn property which is equivalent to countable tightness.

Keywords

countable tightness; c(a)-closure operators; strongly sequentially closed; strongly sequentially open; weak Fr $$\$ chet-Urysohn property;

Citations & Related Records

Times Cited By KSCI : 1 (Citation Analysis)
Times Cited By SCOPUS : 0

Reference
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