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Unfriendly partitions when avoiding vertices of finite degree

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Autor(es):
Aurichi, Leandro Fiorini ; Real, Lucas Silva Sinzato
Número total de Autores: 2
Tipo de documento: Artigo Científico
Fonte: JOURNAL OF LOGIC AND COMPUTATION; v. N/A, p. 8-pg., 2023-11-21.
Resumo

An unfriendly partition of a graph $G = (V,E)$ is a function $c: V \to 2$ such that $|\{x\in N(v): c(x)\neq c(v)\}|\geq |\{x\in N(v): c(x)=c(v)\}|$ for every vertex $v\in V$, where $N(v)$ denotes its neighborhood. It was conjectured by Cowan and Emerson [] that every graph has an unfriendly partition, but Milner and Shelah in [] found counterexamples for that statement by analysing graphs with uncountably many vertices. Curiously, none of their graphs have vertices with finite degree. Therefore, as a natural direction to approach, in this paper we search for the least cardinality of a graph with this property and that admits no unfriendly partitions. Actually, among some other independence results, we conclude that this value cannot be precisely determined within $\textrm {ZFC}$, in the sense that it may vary from model to model of set theory. (AU)

Processo FAPESP: 19/22344-0 - Combinatória infinita e jogos combinatórios
Beneficiário:Leandro Fiorini Aurichi
Modalidade de apoio: Auxílio à Pesquisa - Regular
Processo FAPESP: 23/00595-6 - Grafos infinitos e aplicações de teoria dos conjuntos
Beneficiário:Leandro Fiorini Aurichi
Modalidade de apoio: Auxílio à Pesquisa - Regular
Processo FAPESP: 21/13373-6 - Um estudo de grafos infinitos por meio do problema de determinar Unfriendly Partitions
Beneficiário:Lucas Silva Sinzato Real
Modalidade de apoio: Bolsas no Brasil - Mestrado