Bella, Angelo; Hrusak, Michael(Universitat Politècnica de València, 2020-10-01)
[EN] In this short note we prove the existence (in ZFC) of a completely regular countable disjointly tight irresolvable space by showing that every sub-maximal countable dense subset of 2c is disjointly tight.
Bella, Angelo; Hernández-Gutiérrez, Rodrigo(Universitat Politècnica de València, 2019-04-01)
[EN] In a paper by Bella, Tokgös and Zdomskyy it is asked whether there exists a Tychonoff space X such that the remainder of Cp(X) in some compactification is Menger but not σ-compact. In this paper we prove that it is ...
Bella, Angelo; Spadaro, Santi(Universitat Politècnica de València, 2020-04-03)
[EN] We solve two questions regarding spaces with a (Gδ)-diagonal of rank 2. One is a question of Basile, Bella and Ridderbos about weakly Lindelöf spaces with a Gδ-diagonal of rank 2 and the other is a question of ...
Bella, Angelo; Malykhin, V.I.(Universitat Politècnica de València, 2001-04-01)
[EN] Answering a question of A.V. Arhangel'skii, we show that any extremally disconnected subspace of a compact space with countable tightness is discrete.
Bella, Angelo(Universitat Politècnica de València, 2018-04-02)
[EN] A pseudocompact space is maximal pseudocompact if every strictly finer topology is no longer pseudocompact. The main result here is a counterexample which answers a question rised by Alas, Sanchis and Wilson.
Bella, Angelo; Spadaro, Santi(Universitat Politècnica de València, 2024-04-02)
[EN] A topological space X is selectively highly divergent (SHD) if for every sequence of non-empty open sets { Un : n ∈ ω } of X, we can find xn ∈ Un such that the sequence {xn : n ∈ ω } has no convergent subsequences. ...
Bella, Angelo(Universitat Politècnica de València, 2005-04-01)
[EN] The finite derived set property asserts that any infinite subset of a space has an infinite subset with only finitely many accumulation points. Among other things, we study this property in the case of a function space ...
Arhangelskii, A.V.; Bella, Angelo(Universitat Politècnica de València, 2007-10-01)
[EN] We discuss some properties stronger than Gδ-diagonal. Among other things, we prove that any first countable paratopological group has a Gδ-diagonal of infinite rank and hence also a regular Gδ-diagonal. This answer a ...