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JOURNALS // Vestnik Udmurtskogo Universiteta. Matematika. Mekhanika. Komp'yuternye Nauki // Archive

Vestn. Udmurtsk. Univ. Mat. Mekh. Komp. Nauki, 2015 Volume 25, Issue 2, Pages 180–183 (Mi vuu475)

MATHEMATICS

Example of nonnormal submetrizable space of small cardinality

M. A. Patrakeevab, E. A. Reznichenkoc

a Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences, ul. S. Kovalevskoi, 16, Yekaterinburg, 620219, Russia
b Institute of Mathematics and Computer Sciences, Ural Federal University, ul. Mira, 19, Yekaterinburg, 620002, Russia
c Department of General Topology and Geometry, Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russia

Abstract: In 1976 K. Alster and T. Przymusiński constructed an example of nonnormal completely regular separable and first-countable topological space of cardinality $\aleph_1$. Also they proved a theorem which implies that under Martin's Axiom with negation of continuum hypothesis there is no similar example, which is additionally cometrizable. If we weaken the cometrizability condition to submetrizability, then the similar statement can not be proved: here we construct an example of nonnormal completely regular submetrizable separable first-countable locally countable space of cardinality $\aleph_1$.

Keywords: submetrizable space, nonnormal space, cometrizable space.

UDC: 515.122

MSC: 54G20, 54D15

Received: 19.05.2015

DOI: 10.20537/vm150203



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