English

Overgroups of subsystem subgroups in exceptional groups: nonideal levels

Group Theory 2023-05-30 v2

Abstract

In the present paper, we practicaly complete the solution of the problem on the description of overgroups of the subsystem subgroup E(Δ,R)E(\Delta,R) in the Chevalley group G(Φ,R)G(\Phi,R) over the ring RR, where Φ\Phi is a simply laced root system, and Δ\Delta is its large enough subsystem. Namely we define objects called levels, and show that for any such an overgroup HH there exists a unique level σ\sigma such that E(σ)HStabG(Φ,R)(Lmax(σ))E(\sigma)\le H\le \mathrm{Stab}_{G(\Phi,R)}(L_{\max}(\sigma)), where E(σ)E(\sigma) is an elementary subgroup defined by the level σ\sigma, and Lmax(σ)L_{\max}(\sigma) is the corresponding Lie subalgebra in the Chevalley algebra. Unlike all the previous papers, now levels can be more complicated objects that the nets of ideals.

Keywords

Cite

@article{arxiv.2107.01258,
  title  = {Overgroups of subsystem subgroups in exceptional groups: nonideal levels},
  author = {Pavel Gvozdevsky},
  journal= {arXiv preprint arXiv:2107.01258},
  year   = {2023}
}

Comments

33 pages, no figures, to appear in St.Petersburg Math Journal

R2 v1 2026-06-24T03:51:20.832Z