Some bounds on the Laplacian eigenvalues of token graphs

The k-token graph Fk(G) of a graph G on n vertices is the graph whose vertices are the n k-subsets of vertices from G, two of which are adjacent whenever their symmetric difference is a pair of adjacent vertices in G. It is known that the algebraic connectivity (or second Laplacian eigen- value) of...

Descripción completa

Detalles Bibliográficos
Autores: Dalfó, Cristina, Fiol Mora, Miguel Ángel, Messegué, Arnau
Tipo de recurso: artículo
Estado:Versión enviada para evaluación y publicación
Fecha de publicación:2025
País:España
Institución:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
Repositorio:Recercat. Dipósit de la Recerca de Catalunya
OAI Identifier:oai:recercat.cat:10459.1/467299
Acceso en línea:https://doi.org/10.1016/j.disc.2024.114382
https://hdl.handle.net/10459.1/467299
Access Level:acceso abierto
Palabra clave:Token graph
Laplacian spectrum
Algebraic connectivity
Binomial matrix
Descripción
Sumario:The k-token graph Fk(G) of a graph G on n vertices is the graph whose vertices are the n k-subsets of vertices from G, two of which are adjacent whenever their symmetric difference is a pair of adjacent vertices in G. It is known that the algebraic connectivity (or second Laplacian eigen- value) of Fk(G) equals the algebraic connectivity α(G) of G. In this paper, we give some bounds on the (Laplacian) eigenvalues of the k-token graph (including the algebraic connectivity) in terms of the h-token graph, with h ≤ k. For instance, we prove that if λ is an eigenvalue of Fk(G), but not of G, then λ ≥ kα(G) − k + 1. As a consequence, we conclude that if α(G) ≥ k, then α(Fh(G)) = α(G) for every h ≤ k.