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Bipartite Q-Polynomial Quotients of Antipodal Distance-Regular Graphs

✍ Scribed by John S. Caughman IV

Publisher: Elsevier Science
Year: 1999
Tongue: English
Weight: 91 KB
Volume: 76
Category: Article
ISSN: 0095-8956
DOI: 10.1006/jctb.1999.1911

No coin nor oath required. For personal study only.

✦ Synopsis

Let 1 denote a bipartite Q-polynomial distance-regular graph with diameter D 4. We show that 1 is the quotient of an antipodal distance-regular graph if and only if one of the following holds.

(i) 1 is a cycle of even length.

(ii) 1 is the quotient of the 2D-cube.

1999 Academic Press * , ..., %* D denote the associated dual eigenvalue sequence, and let ;, %* D+1 be as in (1), (2). Suppose %* D&1 =%* D+1 .

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