English

Connectivity of $p$-subgroup posets with irreducible characters

Group Theory 2025-12-30 v1 Combinatorics

Abstract

Let GG be a finite group. For a prime pp and an integer e0e \geq 0, we denote by Γp,e(G)\Gamma_{p,e}(G) the set of all pairs (H,φ)(H, \varphi), where HH is a pp-subgroup of GG of order greater than pep^e and φ\varphi is a complex irreducible character of HH. In this paper, we investigate the connected components of the poset Γp,e(G)\Gamma_{p,e}(G). For the case e=0e = 0, we prove that Γp,0(G)\Gamma_{p,0}(G) is disconnected if and only if either GG has a strongly pp-embedded subgroup, or every Sylow pp-subgroup of GG contains a unique subgroup of order pp. Furthermore, for e=1e = 1 and GG a pp-group, we show that the number of connected components of Γp,1(G)\Gamma_{p,1}(G) equals the order of the intersection of all subgroups of GG of order p2p^2.

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Cite

@article{arxiv.2512.22410,
  title  = {Connectivity of $p$-subgroup posets with irreducible characters},
  author = {Hangyang Meng and Yuting Yang},
  journal= {arXiv preprint arXiv:2512.22410},
  year   = {2025}
}

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16 pages