Small $AT4$-graphs and strongly regular subgraphs corresponding to them
Let $\cal M$ be the class of strongly regular graphs for which $\mu$ is a nonprincipal eigenvalue. Note that the neighborhood of any vertex of an $AT4$-graph lies in $\cal M$. Parameters of graphs from $\cal M$ were described earlier. We find intersection arrays of small $AT4$-graphs and of strongly regular graphs corresponding to them.