Abstract:
Let $\Gamma$ be a distance regular graph of diameter 3 for which the graph
$\Gamma_3$ is a pseudo-network.
Previously, A.A. Makhnev, M.P. Golubyatnikov, Wenbin Guo found infinite series of admissible arrays of
intersections of such graphs. In the case of $c_2 = 1$, we have the two-parameter series
$\{nm-1,nm-n+m-1,n-m+1;1,1,nm-n+m-1\}$.
Possible automorphisms of such graphs were found by
A.A. Makhnev, M.P. Golubyatnikov.
In this paper the author found automorphism groups of distance regular graphs with intersection arrays
$\{90,84,7;1,1,84\}$ ($n=13,m=7$), $\{220,216,5;1,1,216\}$ ($n=17,m=13$), $\{272,264,9;1,1,264\}$ ($n=21,m=13$).
In particular, this graphs are not arc transitive.