Strongly regular graphs with parameters (81, 30, 9, 12) and a new partial geometry

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Department of Mathematical Sciences


Twelve new strongly regular graphs with parameters (81, 30, 9, 12) are found as graphs invariant under certain subgroups of the automorphism groups of the two previously known graphs that arise from 2-weight codes. One of these new graphs is geometric and yields a partial geometry with parameters pg(5, 5, 2) that is not isomorphic to the partial geometry discovered by J. H. van Lint and A. Schrijver [13] in 1981.

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© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature. Publisher’s version of record:

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Journal of Algebraic Combinatorics