Almost Moore and the largest mixed graphs of diameters two and three

Almost Moore mixed graphs appear in the context of the degree/diameter problem as a class of extremal mixed graphs, in the sense that their order is one unit less than the Moore bound for such graphs. The problem of their existence has been considered just for diameter 2. In this paper, we give a co...

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Detalles Bibliográficos
Autores: Dalfó, Cristina, Fiol Mora, Miguel Ángel, López Lorenzo, Ignacio
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2024
País:España
Institución:Universitat de Lleida (UdL)
Repositorio:Repositori Obert UdL
OAI Identifier:oai:repositori.udl.cat:10459.1/465749
Acceso en línea:https://doi.org/10.1016/j.laa.2024.01.007
https://hdl.handle.net/10459.1/465749
Access Level:acceso abierto
Palabra clave:Mixed graph
Degree/diameter problem
Almost Moore graph
Distance matrix
Spectrum
Descripción
Sumario:Almost Moore mixed graphs appear in the context of the degree/diameter problem as a class of extremal mixed graphs, in the sense that their order is one unit less than the Moore bound for such graphs. The problem of their existence has been considered just for diameter 2. In this paper, we give a complete characterization of these extremal mixed graphs for diameters 2 and 3. We also derive some optimal constructions for other diameters.