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This article is cited in 5 scientific papers (total in 5 papers)
Discrete mathematics and mathematical cybernetics
To the theory of Shilla graphs with $b_2=c_2$
A. A. Makhnev, I. N. Belousov Krasovskii Institute of Mathematics and Mechanics,
16 S.Kovalevskaya Str.,
620990, Yekaterinburg, Russia
Abstract:
In this paper by using exact formulas for multiplicities of eigenvalues it is
founded new infinite serie intersection arrays of $Q$-polynomial Shilla graph with
$b_2 = c_2$. Intersection array of $Q$-polynomial Shilla graph $\Gamma$ with $b_2=c_2$ is
$\{2rt(2r+1),(2r-1)(2rt+t+1),r(r+t);1,r(r+t),t(4r^2-1)\}$ and for any vertex $u\in \Gamma$
the subgraph $\Gamma_3(u)$ is an antipodal distance-regular graph with the intersection array
$\{t(2r+1),(2r-1)(t+1),1;1,t+1,t(2r+1)\}$.
In case $t=2r^2-1$ the intersection array is feasible and in case $t=r(2lr-(l+1))$
the intersection array is feasible only if $(l,r)\in \{(1,2),(2,1),(4,1),(6,1)\}$.
Keywords:
distance-regular graph, Shilla graph.
Received October 6, 2017, published November 14, 2017
Citation:
A. A. Makhnev, I. N. Belousov, “To the theory of Shilla graphs with $b_2=c_2$”, Sib. Èlektron. Mat. Izv., 14 (2017), 1135–1146
Linking options:
https://www.mathnet.ru/eng/semr853 https://www.mathnet.ru/eng/semr/v14/p1135
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