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JOURNALS // Vladikavkazskii Matematicheskii Zhurnal // Archive

Vladikavkaz. Mat. Zh., 2024 Volume 26, Number 3, Pages 47–55 (Mi vmj920)

On automorphisms of a graph with an intersection array $\{44,30,9;1,5,36\}$

M. M. Isakovaa, A. A. Makhnevb, Mingzhu Chenc

a Kabardino-Balkarian State University named after H. M. Berbekov, 173 Chernyshevsky St., Nalchik 360004, Russia
b N. N. Krasovskii Institute of Mathematics and Mechanics, 16 S. Kovalevskaya St., Ekaterinburg 620990, Russia
c Hainan University, 58 Renmin Ave., Haikou 570228, China

Abstract: For the set $X$ automorphisms of the graph $\Gamma$ let ${\rm Fix}(X)$ be a set of all vertices of $\Gamma$ fixed by any automorphism from $X$. There are $7$ feasible intersection arrays of distance regular graphs with diameter $3$ and degree $44$. Early it was proved that for fifth of them graphs do not exist. In this paper it is founded possible automorphisms of distance regular graph with intersection array $\{44,30,9;1,5,36\}$. The proof of the theorem is based on Higman’s method of working with automorphisms of a distance regular graph. The consequence of the main result is is the following: Let $\Gamma$ be a distance regular graph with intersection array $\{44,30,9;1,5,36\}$ and the group $G={\rm Aut}(\Gamma)$ acts vertex-transitively; then $G$ acts intransitively on the set arcs of $\Gamma$.

Key words: strongly regular graph, fixed point subgraph, distance regular graph, automorphism.

UDC: 519.17

MSC: 05B05, 20D05

Received: 26.06.2024

DOI: 10.46698/x0578-3097-1488-l



© Steklov Math. Inst. of RAS, 2025