RUS  ENG
Full version
JOURNALS // Sibirskie Èlektronnye Matematicheskie Izvestiya [Siberian Electronic Mathematical Reports] // Archive

Sib. Èlektron. Mat. Izv., 2019 Volume 16, Pages 1385–1392 (Mi semr1137)

This article is cited 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.

UDC: 519.17

MSC: 05C25

Received July 17, 2019, published October 7, 2019

DOI: 10.33048/semi.2019.16.096



Bibliographic databases:


© Steklov Math. Inst. of RAS, 2024