A large family of strongly regular graphs with small Weisfeiler-Leman dimension

Abstract: In 2002, D. Fon-Der-Flaass constructed a prolific family of strongly regular graphs. In this paper, we prove that for infinitely many natural numbers $n$, this family contains $n^{\Omega(n^{2/3})}$ strongly regular $n$-vertex graphs $X$ with the same parameters, which satisfy the following condition: an isomorphism between $X$ and any other graph can be verified by the $4$-dimensional Weisfeiler-Leman algorithm.