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This article is cited in 3 scientific papers (total in 3 papers)
Discrete mathematics and mathematical cybernetics
On $Q$-polynomial distance-regular graphs $\Gamma$ with strongly regular graphs $\Gamma_2$ and $\Gamma_3$
I. N. Belousova, A. A. Makhneva, M. S. Nirovab a N.N. Krasovskii Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences, 16, S.Kovalevskaya str., Yekaterinburg, 620990, Russia
b Kabardino-Balkarian State University named after H.M. Berbekov, 175, Chernyshevsky str., Nalchik, 360004, Russia
Abstract:
Let $\Gamma$ be a distance-regular graph of diameter 3 with strongly regular graphs $\Gamma_2$ and $\Gamma_3$. Then $\Gamma$ has intersection array $\{t(c_2+1)+a_3,tc_2,a_3+1;1,c_2,t(c_2+1)\}$ (Nirova M.S.) If $\Gamma$ is $Q$-polynomial then either $a_3=0,t=1$ and $\Gamma$ is Taylor graph or $(c_2+1)=a_3(a_3+1)/(t^2-a_3-1)$. We found 4 infinite series feasible intersection arrays in this situation.
Keywords:
distance-regular graph, $Q$-polynomial graph.
Received July 17, 2019, published October 7, 2019
Citation:
I. N. Belousov, A. A. Makhnev, M. S. Nirova, “On $Q$-polynomial distance-regular graphs $\Gamma$ with strongly regular graphs $\Gamma_2$ and $\Gamma_3$”, Sib. Èlektron. Mat. Izv., 16 (2019), 1385–1392
Linking options:
https://www.mathnet.ru/eng/semr1137 https://www.mathnet.ru/eng/semr/v16/p1385
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