Abstract:
Using R. Wilson's recent results, we prove the existence of triples $(\mathfrak{X},G,H)$ such that $\mathfrak{X}$ is a complete (i.e., closed under taking subgroups, homomorphic images, and extensions) class of finite groups, $G$ is a finite simple group, and $H$ is its $\mathfrak{X}$-maximal subgroup nonpronormal in $G$. This disproves a conjecture stated earlier by the second author and W. Guo.
Keywords:complete class of groups, relatively maximal subgroup, pronormal subgroup, finite simple group.
The research of B. Li was supported by National Natural Science Foundation of China, (NSFC), grant no.12371021. The research of D. O. Revin was carried out within the State Contract of the Sobolev Institute of Mathematics (FWNF-2022-0002).