English

An infinite family of counterexamples to the Polycirculant Conjecture

Group Theory 2026-07-26 v1 Combinatorics

Abstract

We disprove the Polycirculant Conjecture, which states that every transitive 2-closed permutation group is non-elusive, i.e. contains a derangement of prime order. In fact, we prove a stronger result, answering a long-standing question of Maru\v{s}i\v{c} and Jordan: there exists a vertex-transitive graph admitting no semiregular automorphism. To do so, we employ recently developed methods of Chen et al. for constructing elusive groups via non-split extensions, allowing us to construct an elusive group 76.PSU3(3)7^6.\mathrm{PSU}_3(3) of degree 16,464. We show that this group is the full automorphism group of seven of its orbital graphs and hence is 2-closed. Our example extends to infinitely many counterexamples of the Polycirculant Conjecture, and infinitely many vertex-transitive graphs admitting no semiregular automorphism.

Keywords

Cite

@article{arxiv.2607.23423,
  title  = {An infinite family of counterexamples to the Polycirculant Conjecture},
  author = {Saul D. Freedman and Melissa Lee},
  journal= {arXiv preprint arXiv:2607.23423},
  year   = {2026}
}

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11 pages