A quasi-spectral characterization of strongly distance-regular graphs
The electronic journal of combinatorics, Tome 7 (2000)
A graph $\Gamma$ with diameter $d$ is strongly distance-regular if $\Gamma$ is distance-regular and its distance-$d$ graph $\Gamma _d$ is strongly regular. The known examples are all the connected strongly regular graphs (i.e. $d=2$), all the antipodal distance-regular graphs, and some distance-regular graphs with diameter $d=3$. The main result in this paper is a characterization of these graphs (among regular graphs with $d$ distinct eigenvalues), in terms of the eigenvalues, the sum of the multiplicities corresponding to the eigenvalues with (non-zero) even subindex, and the harmonic mean of the degrees of the distance-$d$ graph.
DOI :
10.37236/1529
Classification :
05E30, 05C50, 05C75
Mots-clés : distance-regular graphs, strongly regular graph, spectral characterization
Mots-clés : distance-regular graphs, strongly regular graph, spectral characterization
@article{10_37236_1529,
author = {M. A. Fiol},
title = {A quasi-spectral characterization of strongly distance-regular graphs},
journal = {The electronic journal of combinatorics},
year = {2000},
volume = {7},
doi = {10.37236/1529},
zbl = {0956.05103},
url = {http://geodesic.mathdoc.fr/articles/10.37236/1529/}
}
M. A. Fiol. A quasi-spectral characterization of strongly distance-regular graphs. The electronic journal of combinatorics, Tome 7 (2000). doi: 10.37236/1529
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