A spectral excess theorem for digraphs with normal Laplacian matrices

Autor: Fateme Shafiei

Publikováno v: Transactions on Combinatorics, Vol 7, Iss 3, Pp 19-28 (2018)

The spectral excess theorem‎, ‎due to Fiol and Garriga in 1997‎, ‎is an important result‎, ‎because it gives a good characterization‎ ‎of distance-regularity in graphs‎. ‎Up to now‎, ‎some authors have given some variations of

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A spectral excess theorem for nonregular graphs

Autor: Guang-Siang Lee, Chih-wen Weng

Publikováno v: Journal of Combinatorial Theory, Series A. 119:1427-1431

The spectral excess theorem asserts that the average excess is, at most, the spectral excess in a regular graph, and equality holds if and only if the graph is distance-regular. An example demonstrates that this theorem cannot directly apply to nonre

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https://doi.org/10.1016/j.jcta.2012.04.002

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Edge distance-regular graphs

Autor: Marc Cámara, Cristina Dalfó, E. Garriga, J. Fíbrega, Miguel Angel Fiol

Publikováno v: Recercat. Dipósit de la Recerca de Catalunya
instname
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Repositorio Abierto de la UdL
Universitad de Lleida

Edge-distance-regularity is a concept recently introduced by the authors which is similar to that of distance-regularity, but now the graph is seen from each of its edges instead of from its vertices. More precisely, a graph Γ with adjacency matrix

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2692d4f16508e3e355766926efcf3a0f
https://hdl.handle.net/10459.1/72557