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JOURNALS // Sibirskii Matematicheskii Zhurnal // Archive

Sibirsk. Mat. Zh., 2008 Volume 49, Number 1, Pages 161–182 (Mi smj1830)

This article is cited in 3 papers

Strongly regular locally $GQ(4,t)$-graphs

A. A. Makhnev

Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences

Abstract: Amply regular with parameters $(v,k,\lambda,\mu)$ we call an undirected graph with $v$ vertices in which the degrees of all vertices are equal to $k$, every edge belongs to $\lambda$ triangles, and the intersection of the neighborhoods of every pair of vertices at distance 2 contains exactly $\mu$ vertices. An amply regular diameter 2 graph is called strongly regular. We prove the nonexistence of amply regular locally $GQ(4,t)$-graphs with $(t,\mu)=(4,10)$ and $(8,30)$. This reduces the classification problem for strongly regular locally $GQ(4,t)$-graphs to studying locally $GQ(4,6)$-graphs with parameters $(726,125,28,20)$.

Keywords: strongly regular graph, generalized quadrangle, hyperoval.

UDC: 519.14

Received: 09.06.2006


 English version:
Siberian Mathematical Journal, 2008, 49:1, 130–146

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