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JOURNALS // Trudy Instituta Matematiki i Mekhaniki UrO RAN // Archive

Trudy Inst. Mat. i Mekh. UrO RAN, 2017 Volume 23, Number 4, Pages 119–127 (Mi timm1472)

This article is cited in 1 paper

Automorphisms of an $AT4(4,4,2)$-graph and of the corresponding strongly regular graphs

K. S. Efimovabc

a Ural Federal University, Ekaterinburg, 620002 Russia
b Ural State University of Economics, Ekaterinburg, 620144 Russia
c Krasovskii Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, 620990 Russia

Abstract: A.A. Makhnev, D.V. Paduchikh, and M. M. Khamgokova gave a classification of distance-regular locally\linebreak $GQ(5,3)$-graphs. In particular, there arises an $AT4(4,4,2)$-graph with intersection array $\{96,75,16,1;1,16,75,96\}$ on $644$ vertices. The same authors proved that an $AT4(4,4,2)$-graph is not a locally $GQ(5,3)$-graph. However, the existence of an $AT4(4,4,2)$-graph that is a locally pseudo $GQ(5,3)$-graph is unknown. The antipodal quotient of an $AT4(4,4,2)$-graph is a strongly regular graph with parameters $(322,96,20,32)$. These two graphs are locally pseudo $GQ(5,3)$-graphs. We find their possible automorphisms. It turns out that the automorphism group of a distance-regular graph with intersection array $\{96,75,16,1;1,16,75,96\}$ acts intransitively on the set of its antipodal classes.

Keywords: distance-regular graph, graph automorphism.

UDC: 519.17

MSC: 05B25

Received: 01.09.2017

DOI: 10.21538/0134-4889-2017-23-4-119-127


 English version:
Proceedings of the Steklov Institute of Mathematics (Supplement Issues), 2019, 304, suppl. 1, S59–S67

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