Spectral properties of mixed radial Moore graphs

J.M. Ceresuela, Cristina Dalfó, M.A. Fiol, Nacho López, J.M. Miret

Abstract


The pioneering study of Moore graphs by Hoffman and Singleton exploits the properties of the eigenvalues of the adjacency matrix of graphs. Radial Moore graphs are extremal graphs related to the Moore ones, where the distance-preserving spanning tree is preserved for some vertices. In this paper, we present some equations involving the adjacency matrix of a mixed radial Moore graph. These equations are used as a basis to create some spectral measures that lead us to rank mixed radial Moore graphs and show which graph is the closest graph to being a mixed Moore graph.

Keywords


mixed graph; radial Moore graph; degree/diameter problem; distance matrix; spectrum

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DOI: http://dx.doi.org/10.5614/ejgta.2026.14.2.12

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