Abstract
In this paper new characterizations of semi-R0 and semi-R1 spaces are obtained and used to prove that the product space of semi-R0, semi-T1, and semi-T0 spaces is, respectively, semi-R0, semi-T1, and semi-T0; and that the product space of semi-R1 space need not be semi-R1. An example is given where the product space is semi-T2 and one of the factor spaces is not semi-T0 or semi-R0.
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Dorsett, C. Product spaces and semi-separation axioms. Period Math Hung 13, 39–45 (1982). https://doi.org/10.1007/BF01848095
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DOI: https://doi.org/10.1007/BF01848095