Free sequences and the tightness of pseudoradial spaces

Santi Domenico Spadaro, Santi Spadaro

Risultato della ricerca: Articlepeer review

Abstract

Let F(X) be the supremum of cardinalities of free sequences in X. We prove that the radial character of every Lindelöf Hausdorff almost radial space X and the set-tightness of every Lindelöf Hausdorff space are always bounded above by F(X). We then improve a result of Dow, Juhász, Soukup, Szentmiklóssy and Weiss by proving that if X is a Lindelöf Hausdorff space, and Xδ denotes the Gδ topology on X then t(Xδ) ≤ 2 t ( X ). Finally, we exploit this to prove that if X is a Lindelöf Hausdorff pseudoradial space then F(Xδ) ≤ 2 F ( X ).
Lingua originaleEnglish
Numero di pagine6
RivistaREVISTA DE LA REAL ACADEMIA DE CIENCIAS EXACTAS, FÍSICAS Y NATURALES. SERIE A, MATEMÁTICAS
Volume114
Stato di pubblicazionePublished - 2020

All Science Journal Classification (ASJC) codes

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  • ???subjectarea.asjc.2600.2608???
  • ???subjectarea.asjc.2600.2605???
  • ???subjectarea.asjc.2600.2604???

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