Angelo Bella

activity

20142020

collaborators

4 papers

math.GN2020

A common extension of Lindelöf, H-closed and ccc

Angelo Bella

The inequality $∣ X ∣ \leq 2^{χ (X)}$ has been proved to be true for Lindelöf spaces (Arhangel'ski\uı, 1969), $H$ -closed spaces (Dow-Porter, 1982) and ccc spaces (Hajnal-Juász 1967),…

math.GN2020

Upper bounds for the tightness of the $G_{δ}$ -topology

Angelo Bella, Santi Spadaro

We prove that if $X$ is a regular space with no uncountable free sequences, then the tightness of its $G_{δ}$ topology is at most continuum and if $X$ is in addition Lindelöf then it…

math.GN2016

On cardinality bounds involving the weak Lindelöf degree

Angelo Bella, Nathan Carlson

We give a general closing-off argument in Theorem 2.1 from which several corollaries follow, including (1) if $X$ is a locally compact Hausdorff space then $∣ X ∣ \leq 2^{w L (X) ψ (X)}$ ,…

math.GN2014

When is a space Menger at infinity?

Leandro F. Aurichi, Angelo Bella

We try to characterize those Tychonoff spaces $X$ such that $β X ∖ X$ has the Menger property.

A common extension of Lindelöf, H-closed and ccc

Upper bounds for the tightness of the Gδ​-topology

On cardinality bounds involving the weak Lindelöf degree

When is a space Menger at infinity?

Upper bounds for the tightness of the $G_{δ}$ -topology