| Texto completo | |
| Autor(es): |
Tomita, Artur Hideyuki
;
Trianon-Fraga, Juliane
Número total de Autores: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Topology and its Applications; v. 327, p. 31-pg., 2023-02-02. |
| Resumo | |
In 1990, Comfort asked: is there, for every cardinal number alpha < 2c, a topological group G such that G gamma is countably compact for all cardinals -y < alpha, but G alpha is not countably compact? A similar question can also be asked for countably pracompact groups: for which cardinals alpha is there a topological group G such that G gamma is countably pracompact for all cardinals -y < alpha, but G alpha is not countably pracompact? In this paper we construct such group in the case alpha = w, assuming the existence of c incomparable selective ultrafilters, and in the case alpha = iota c+, with w < iota c < 2c, assuming the existence of 2c incomparable selective ultrafilters. In particular, under the second assumption, there exists a topological group G so that G2c is countably pracompact, but G(2c)+ is not countably pracompact, unlike the countably compact case. (AU) | |
| Processo FAPESP: | 21/00177-4 - Espaços topológicos e conjuntos |
| Beneficiário: | Artur Hideyuki Tomita |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 19/12628-0 - Pseudocompacidade e ultrafiltros |
| Beneficiário: | Juliane Trianon Fraga |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |