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Sibirskii Matematicheskii Zhurnal, 2015, Volume 56, Number 2, Pages 368–376
(Mi smj2643)
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Some generalization of the Arkhangel'skiĭ–Kombarov theorem for seminormal functors
A. V. Ivanov Petrozavodsk State University, Faculty of Mathematics, Petrozavodsk, Russia
Abstract:
We introduce the notion of variative seminormal functor $\mathscr F$ and prove that, for each of these functors and every compact space $X$, the normality of the space $\mathscr F(X)\setminus X$ is countable. Thus, we obtain a generalization of the Arkhangel'skiĭ–Kombarov theorem of 1990 on the countability of the character of a compact space which is normal outside the diagonal. Under the assumption of Jensen's principle, we prove that the above assertion fails for finite nonvariative functors.
Keywords:
seminormal functor, Arkhangelskiĭ–Kombarov theorem, first-countability, normality outside the diagonal.
Received: 16.11.2013
Citation:
A. V. Ivanov, “Some generalization of the Arkhangel'skiĭ–Kombarov theorem for seminormal functors”, Sibirsk. Mat. Zh., 56:2 (2015), 368–376; Siberian Math. J., 56:2 (2015), 297–303
Linking options:
https://www.mathnet.ru/eng/smj2643 https://www.mathnet.ru/eng/smj/v56/i2/p368
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Abstract page: | 220 | Full-text PDF : | 64 | References: | 50 | First page: | 7 |
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