arXiv subjects

Julio César Hernández Arzusa

Publications and source records attributed to Julio César Hernández Arzusa.

4 recordsLinked to original sources

arXiv2026

Reflections and Sheafifications in Algebraic and Topological Categories

In this article, we develop an explicit categorical realization of sheafification based on colimits, products, and subobjects, emphasizing its behavior in algebraic and topological-algebraic settings. We prove that if $\mathcal{C}$ is a reflective subcategory of a category $\mathcal{A}$, then the presheaf category $\mathbf{Psh}(X,\mathcal{C})$ is reflective in $\mathbf{Psh}(X,\mathcal{A})$. We further investigate the interaction between reflections and sheafification, obtaining natural conditions under which these constructions are naturally isomorphic.

math.GN↗

arXiv2020

Pseudocompact and precompact subsemigroups of topological groups

In this paper we give sufficient conditions under which a subsemigroup of a topological group is a subgroup, adding to the results given in \cite{Kosh, can, axioms, forum, Hof, cc, locally} where conditions exist (such as locally compactness, compactness, feeble compactness and sequential compactness) for a semigroup to be a group. In our work we proved that closed precompact subsemigroups of topological groups are semigroups, just like open pseudocompact monoids of topological groups.

math.GN↗

arXiv2020

A Note on Locally Compact Subsemigroups of Compact Groups

An elementary proof is given for the fact that every locally compact subsemigroup of a compact topological group is a closed subgroup. A sample consequence is that every commutative cancellative pseudocompact locally compact Hausdorff topological semigroup with open shifts is a compact topological group.

math.GN↗

arXiv2020

Toplogical semigroups embedded into topological groups

In this paper we give conditions under which a topological semigroup can be embedded algebraically and topologically into a compact topological group. We prove that every feebly compact regular first countable cancellative commutative topological semigroup with open shifts is a topological group, as well as every connected locally compact Hausdorff cancellative commutative topological monoid with open shifts. Finally, we use these results to give sufficient conditions on a topological semigroup that guarantee it to have countable cellularity.

math.GN↗