Nonexistence of exceptional imprimitive Q-polynomial association schemes with six classes
Combinatorics
2010-12-30 v1
Abstract
Suzuki (1998) showed that an imprimitive Q-polynomial association scheme with first multiplicity at least three is either Q-bipartite, Q-antipodal, or with four or six classes. The exceptional case with four classes has recently been ruled out by Cerzo and Suzuki (2009). In this paper, we show the nonexistence of the last case with six classes. Hence Suzuki's theorem now exactly mirrors its well-known counterpart for imprimitive distance-regular graphs.
Keywords
Cite
@article{arxiv.1005.3598,
title = {Nonexistence of exceptional imprimitive Q-polynomial association schemes with six classes},
author = {Hajime Tanaka and Rie Tanaka},
journal= {arXiv preprint arXiv:1005.3598},
year = {2010}
}
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7 pages