A characterization of the countable paracompactness for products of ordinals

Autor:	Yukinobu Yajima, Yasushi Hirata
Rok vydání:	2020
Předmět:	Combinatorics Mathematics::Logic Product (mathematics) Mathematics::General Topology Countable set Uncountable set Geometry and Topology Rectangle Paracompact space Characterization (mathematics) Linear subspace Mathematics
Zdroj:	Topology and its Applications. 282:107325
ISSN:	0166-8641
DOI:	10.1016/j.topol.2020.107325
Popis:	Let A and B be two subspaces of an ordinal. It is proved that the product A × B is countably paracompact if and only if for every regular uncountable cardinal κ and for every closed rectangle A ′ × B ′ in A × B , either A ′ or B ′ contains a closed discrete subset of size κ whenever so does A ′ × B ′ . This characterization of the countably paracompact products of ordinals is much simpler than the previous one given in 1992.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::b08a3cce59f229742038b494824134c8 https://doi.org/10.1016/j.topol.2020.107325 Zobrazit plný text záznamu Full Text from ScienceDirect