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Distance-Regular Graphs withbt=1 and Antipodal Double-Covers

✍ Scribed by Makoto Araya; Akira Hiraki; Aleksandar Jurišić

Publisher
Elsevier Science
Year
1996
Tongue
English
Weight
239 KB
Volume
67
Category
Article
ISSN
0095-8956

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✦ Synopsis

Let 1 be a distance-regular graph of diameter d and valency k>2. If b t =1 and 2t d, then 1 is an antipodal double-cover. Consequently, if f >2 is the multiplicity of an eigenvalue of the adjacency matrix of 1 and if 1 is not an antipodal doublecover then d 2f&3. This result is an improvement of Godsil's bound. 1996 Academic Press, Inc.

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