English

A generalisation of Schenkman's theorem

Group Theory 2022-12-13 v1

Abstract

Let GG be a finite group and let F\mathfrak{F} be a hereditary saturated formation. We denote by ZF(G)\mathbf{Z}_{\mathfrak{F}}(G) the product of all normal subgroups NN of GG such that every chief factor H/KH/K of GG below NN is F\mathfrak{F}-central in GG, that is, (H/K)(G/CG(H/K))F. (H/K) \rtimes (G/\mathbf{C}_{G}(H/K)) \in \mathfrak{F}. A subgroup AGA \leq G is said to be F\mathfrak{F}-subnormal in the sense of Kegel, or KK-F\mathfrak{F}-subnormal in GG, if there is a subgroup chain A=A0A1An=G A = A_0 \leq A_1 \leq \ldots \leq A_n = G such that either Ai1AiA_{i-1} \trianglelefteq A_{i} or Ai/(Ai1)AiFA_i / (A_{i-1})_{A_i} \in \mathfrak{F} for all i=1,,ni = 1, \ldots , n. In this paper, we prove the following generalisation of Schenkman's Theorem on the centraliser of the nilpotent residual of a subnormal subgroup: Let F\mathfrak{F} be a hereditary saturated formation and let SS be a KK-F\mathfrak{F}-subnormal subgroup of GG. If ZF(E)=1\mathbf{Z}_{\mathfrak{F}}(E) = 1 for every subgroup EE of GG such that SES \leq E then CG(D)D\mathbf{C}_{G}(D) \leq D, where D=SFD = S^{\mathfrak{F}} is the F\mathfrak{F}-residual of SS.

Keywords

Cite

@article{arxiv.2009.08145,
  title  = {A generalisation of Schenkman's theorem},
  author = {Stefanos Aivazidis and Ina N. Safonova and Alexander N. Skiba},
  journal= {arXiv preprint arXiv:2009.08145},
  year   = {2022}
}

Comments

9 pages

R2 v1 2026-06-23T18:36:29.293Z