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Pseudocyclic association schemes arising from the actions of PGL(2,2^m) and PΓL(2,2^m)

Henk D. L. Hollmann·Qing Xiang
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Abstract

The action of $PGL(2,2^m)$ on the set of exterior lines to a nonsingular conic in $PG(2,2^m)$ affords an association scheme, which was shown to be pseudocyclic in Hollmann's thesis in 1982. It was further conjectured in Hollmann's thesis that the orbital scheme of $PΓL(2,2^m)$ on the set of exterior lines to a nonsingular conic in $PG(2,2^m)$ is also pseudocyclic if $m$ is an odd prime. We confirm this conjecture in this paper. As a by-product, we obtain a class of Latin square type strongly regular graphs on nonprime-power number of points.

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Henk D. L. Hollmann, Qing Xiang. 2005-03-24. Pseudocyclic association schemes arising from the actions of PGL(2,2^m) and PΓL(2,2^m). https://arxiv.org/abs/math/0503570

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