A characterization of two classes of strongly regular graphs
Let \(G\) be a strongly regular graph with classical parameters \((2, q^ 2, s(q+ 1), \beta)\) according to Neumaier, see [\textit{A. E. Brouwer}, \textit{A. M. Cohen} and \textit{A. Neumaier}, Distance-regular graphs (1989; Zbl 0747.05073)]. It is proved that with some extra conditions related to the geometrical structure of \(G\), \(q\) is prime and either \(G\) is isomorphic to the half dual polar graph \(D_{4, 4}(q)\) or to the alternating forms graph \(\text{Alt}(4, q)\).
scientific article; zbMATH DE number 739181