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Automorphisms of strongly regular graphs with parameters $(1305,440,115,165)$
A. A. Makhnevab, D. V. Paduchikha, M. M. Khamgokovaa a Krasovskii Institute of Mathematics and Mechanics,
Ural Branch of the Russian Academy of Sciences, Yekaterinburg, 620990 Russia
b Ural Federal University, Ekaterinburg, 620002 Russia
Abstract:
A graph $\varGamma$ is called $t$-isoregular if, for any $i\le t$ and any $i$-vertex subset $S$, the number $\varGamma(S)$ depends only on the isomorphism class of the subgraph induced by $S$. A graph $\varGamma$ on $v$ vertices is called absolutely isoregular if it is $(v-1)$-isoregular. It is known that each $5$-isoregular graph is absolutely isoregular, and such graphs have been fully described. Each exactly $4$-isoregular graph is either a pseudogeometric graph for pG$_r(2r,2r^3+3r^2-1)$ or its complement. By Izo$(r)$ we denote a pseudogeometric graph for pG$_r(2r,2r^3+3r^2-1)$. Graphs Izo$(r)$ do not exist for an infinite set of values of $r$ ($r=3,4,6,10,\ldots$). The existence of Izo$(5)$ is unknown. In this work we find possible automorphisms for the neighborhood of an edge from Izo$(5)$.
Keywords:
isoregular graph, strongly regular graph, pseudogeometric graph.
Received: 24.04.2017
Citation:
A. A. Makhnev, D. V. Paduchikh, M. M. Khamgokova, “Automorphisms of strongly regular graphs with parameters $(1305,440,115,165)$”, Trudy Inst. Mat. i Mekh. UrO RAN, 23, no. 4, 2017, 232–242; Proc. Steklov Inst. Math. (Suppl.), 304, suppl. 1 (2019), S112–S122
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https://www.mathnet.ru/eng/timm1482 https://www.mathnet.ru/eng/timm/v23/i4/p232
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Abstract page: | 205 | Full-text PDF : | 42 | References: | 39 | First page: | 5 |
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