On the classification of triply-transitive strongly-regular graphs
Abstract
Let be a strongly-regular graph with adjacency matrix , and let be the adjacency matrix of its complement. For any vertex , we define and to be respectively the diagonal matrices whose main diagonal is the row corresponding to in the matrices , and . The Terwilliger algebra of with respect to the vertex is the subalgebra of the complex matrix algebra . The algebra contains the subspace . In addition, if , then is a subalgebra of the centralizer algebra . The strongly-regular graph is triply transitive if is vertex transitive and , for any . In this paper, we classify all triply transitive strongly-regular graphs that are not isomorphic to the collinearity graph of the polar space , where is a prime power, or the affine polar graph , where and .
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Cite
@article{arxiv.2507.14320,
title = {On the classification of triply-transitive strongly-regular graphs},
author = {Allen Herman and Roghayeh Maleki and Andriaherimanana Sarobidy Razafimahatratra},
journal= {arXiv preprint arXiv:2507.14320},
year = {2025}
}
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48 pages