On large regular (1, 1, k)-mixed graphs

An (r,z,k)-mixed graph G has every vertex with undirected degree r, directed in- and out-degree z, and diameter k. In this paper, we study the case r = z = 1, proposing some new constructions of (1,1,k)-mixed graphs with a large number of vertices N. Our study is based on computer techniques for sma...

Full description

Bibliographic Details
Authors: Dalfó, Cristina, Erskine, G., Exoo, G., Fiol Mora, Miguel Ángel, López Lorenzo, Ignacio, Massegué Buisan, Arnau, Tuite, J.
Format: article
Status:Published version
Publication Date:2024
Country:España
Institution:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
Repository:Recercat. Dipósit de la Recerca de Catalunya
OAI Identifier:oai:recercat.cat:10459.1/466203
Online Access:https://doi.org/10.1016/j.dam.2024.06.001
https://hdl.handle.net/10459.1/466203
Access Level:Open access
Keyword:Mixed graph
Moore bound
Cayley graph
Lift graph
Description
Summary:An (r,z,k)-mixed graph G has every vertex with undirected degree r, directed in- and out-degree z, and diameter k. In this paper, we study the case r = z = 1, proposing some new constructions of (1,1,k)-mixed graphs with a large number of vertices N. Our study is based on computer techniques for small values of k and the use of graphs on alphabets for general k. In the former case, the constructions are either Cayley or lift graphs. In the latter case, some infinite families of (1,1,k)-mixed graphs are proposed with diameter of the order of 2log2 N.