English

Multiple transitivity except for a system of imprimitivity

Group Theory 2024-08-12 v3

Abstract

Let Ω\Omega be a set equipped with an equivalence relation \sim; we refer to the equivalence classes as blocks of Ω\Omega. A permutation group GSym(Ω)G \le \mathrm{Sym}(\Omega) is kk-by-block-transitive if \sim is GG-invariant, with at least kk blocks, and GG is transitive on the set of kk-tuples of points such that no two entries lie in the same block. The action is block-faithful if the action on the set of blocks is faithful. In this article we classify the finite block-faithful 22-by-block-transitive actions. We also show that for k3k \ge 3, there are no finite block-faithful kk-by-block-transitive actions with nontrivial blocks.

Keywords

Cite

@article{arxiv.2211.06848,
  title  = {Multiple transitivity except for a system of imprimitivity},
  author = {Colin D. Reid},
  journal= {arXiv preprint arXiv:2211.06848},
  year   = {2024}
}

Comments

42 pages; journal accepted version

R2 v1 2026-06-28T05:44:48.520Z