English

Non-split sharply 2-transitive groups of bounded exponent

Group Theory 2025-09-17 v2

Abstract

We construct here the first known examples of non-split sharply 2-transitive groups of bounded exponent in odd positive characteristic for every large enough prime p3(mod4)p \equiv 3 \pmod{4}. In fact, we show that there are countably many pairwise non-isomorphic countable non-split sharply 2-transitive groups of characteristic pp for each such pp. Furthermore, we construct non-periodic non-split sharply 2-transitive groups (of these same characteristics) with centralizers of involutions of bounded exponent. As a consequence of these results, we answer two open questions about sharply 2-transitive and 2-transitive permutation groups. The constructions of groups as announced rely on iteratively applying (geometric) small cancellation methods in the presence of involutions. To that end, we develop a method to control some small cancellation parameters in the presence of even-order torsion.

Keywords

Cite

@article{arxiv.2509.11958,
  title  = {Non-split sharply 2-transitive groups of bounded exponent},
  author = {Marco Amelio},
  journal= {arXiv preprint arXiv:2509.11958},
  year   = {2025}
}

Comments

57 pages

R2 v1 2026-07-01T05:36:56.830Z