On convergence structures in graphs

Fuente: arXiv
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Main Authors: Junior, Paulo Magalhães, Mezabarba, Renan Maneli, Monteiro, Rodrigo Santos
Format: Preprint
Published: 2025
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author Junior, Paulo Magalhães
Mezabarba, Renan Maneli
Monteiro, Rodrigo Santos
author_facet Junior, Paulo Magalhães
Mezabarba, Renan Maneli
Monteiro, Rodrigo Santos
contents A closure operator on a set $X$ is a function $\operatorname{cl}: \wp(X) \to \wp(X)$ satisfying, for all $A, B \subseteq X$, the following properties: extensivity, $A \subseteq \operatorname{cl}(A)$; monotonicity, which states that if $A \subseteq B$ then $\operatorname{cl}(A) \subseteq \operatorname{cl}(B)$; and preservation of unions, $\operatorname{cl}(A \cup B) = \operatorname{cl}(A) \cup \operatorname{cl}(B)$. Every graph $G$ naturally carries such an operator on its vertex set by assigning to each subset $A \subseteq V(G)$ the set $\operatorname{cl}(A) = A \cup N(A)$, where $N(A)$ denotes the vertices adjacent to a vertex in $A$. Since closure operators and pretopological spaces are equivalent notions, this operator induces a canonical convergence structure on $V(G)$. We describe this convergence in terms of nets and relate combinatorial properties of the graph to convergence-theoretic ones.
format Preprint
id arxiv_https___arxiv_org_abs_2510_06336
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On convergence structures in graphs
Junior, Paulo Magalhães
Mezabarba, Renan Maneli
Monteiro, Rodrigo Santos
Combinatorics
General Topology
A closure operator on a set $X$ is a function $\operatorname{cl}: \wp(X) \to \wp(X)$ satisfying, for all $A, B \subseteq X$, the following properties: extensivity, $A \subseteq \operatorname{cl}(A)$; monotonicity, which states that if $A \subseteq B$ then $\operatorname{cl}(A) \subseteq \operatorname{cl}(B)$; and preservation of unions, $\operatorname{cl}(A \cup B) = \operatorname{cl}(A) \cup \operatorname{cl}(B)$. Every graph $G$ naturally carries such an operator on its vertex set by assigning to each subset $A \subseteq V(G)$ the set $\operatorname{cl}(A) = A \cup N(A)$, where $N(A)$ denotes the vertices adjacent to a vertex in $A$. Since closure operators and pretopological spaces are equivalent notions, this operator induces a canonical convergence structure on $V(G)$. We describe this convergence in terms of nets and relate combinatorial properties of the graph to convergence-theoretic ones.
title On convergence structures in graphs
topic Combinatorics
General Topology
url https://arxiv.org/abs/2510.06336