English

Subgroups of simple groups are as diverse as possible

Group Theory 2022-03-14 v2

Abstract

For a finite group GG, let σ(G)\sigma(G) be the number of subgroups of GG and σι(G)\sigma_\iota(G) the number of isomorphism types of subgroups of GG. Let L=Lr(pe)L=L_r(p^e) denote a simple group of Lie type, rank rr, over a field of order pep^e and characteristic pp. If r1r\neq 1, L≇2B2(21+2m)L\not\cong {^2 B_2}(2^{1+2m}), then there are constants c,dc,d, dependent on the Lie type, such that as rere grows p(co(1))r4e2σι(Lr(pe))σ(Lr(pe))p(d+o(1))r4e2.p^{(c-o(1))r^4e^2}\leq\sigma_{\iota}(L_r(p^e))\leq\sigma(L_r(p^e)) \leq p^{(d+o(1))r^4e^2}. For type AA, c=d=1/64c=d=1/64. For other classical groups 1/64cd1/41/64\leq c\leq d\leq 1/4. For exceptional and twisted groups 1/2100cd1/41/2^{100}\leq c\leq d\leq 1/4. Furthermore, 2(1/36o(1))k2)σι(Altk)σ(Altk)24(1/6+o(1))k2.2^{(1/36-o(1))k^2)}\leq\sigma_{\iota}(\mathrm{Alt}_k)\leq \sigma(\mathrm{Alt}_k)\leq 24^{(1/6+o(1))k^2}. For abelian and sporadic simple groups GG, σι(G),σ(G)O(1)\sigma_{\iota}(G),\sigma(G)\in O(1). In general these bounds are best possible amongst groups of the same orders. Thus with the exception of finite simple groups with bounded ranks and field degrees, the subgroups of finite simple groups are as diverse as possible.

Keywords

Cite

@article{arxiv.2007.10439,
  title  = {Subgroups of simple groups are as diverse as possible},
  author = {Martin Kassabov and Brady A. Tyburski and James B. Wilson},
  journal= {arXiv preprint arXiv:2007.10439},
  year   = {2022}
}
R2 v1 2026-06-23T17:15:47.298Z