The prime-graph complement characterization for strictly T-solvable groups

Let TT be a nonabelian finite simple group and let kk be a prime number. For each χIBrk(T)\chi\in\operatorname{IBr}_k(T), define AχA_{\chi} to be the set of edges

{kqthere \existsgT such that o(g)=q and 1o(g)xgχ(x)>0}.\{k-q \mid \textnormal{there \exists a } g\in T \textnormal{ such that } \operatorname{o}(g) = q \textnormal{ and } \frac{1}{\operatorname{o}(g)}\sum_{x \in \langle g \rangle}\chi(x) > 0\}.

Prime-graph complement characterization. For every strictly TT-solvable group GG, there exists a set Ypπ(T)IBrp(T)Y\subseteq\bigcup_{p\in\pi(T)}\operatorname{IBr}_p(T) such that

Γ(G)[π(T)]=Γ(T)(χYAχ).\operatorname{\overline{\Gamma}}(G)[\pi(T)] = \operatorname{\overline{\Gamma}}(T)\setminus\left(\bigcup_{\chi\in Y}A_\chi\right).

This proposes a uniform description of the induced prime-graph complement on the set of prime divisors of TT for strictly TT-solvable groups, in terms of the prime-graph complement of TT and the edge sets arising from Brauer characters. The source presents it as a direction for future work; no resolution is supplied.

Sources & referencesView supporting material

Primary source

Thomas Michael Keller, Zachary Martin, Alexa Renner, Gabriel Roca and Eric Yu, “Classification of the Prime Graphs of Sz(8)-, Sz(32)-, and PSL(2, 2^5)-Solvable Groups”, arXiv:2410.21063 (2024).

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