On solvable factors of almost simple groups

Tim C Burness, Cai Heng Li

Research output: Contribution to journalArticle (Academic Journal)peer-review


Let G be a finite almost simple group with socle G0. A (nontrivial) factorization of G is an expression of the form G = HK, where the factors H and K are core-free subgroups. There is an extensive literature on factorizations of almost simple groups, with important applications in permutation group theory and algebraic graph theory. In a recent paper, Li and Xia describe the factorizations of almost simple groups with a solvable factor H. Several infinite families arise in the context of classical groups and in each case a solvable subgroup of G0 containing H \ G0 is identified. Building on this earlier work, in this paper we compute a sharp lower bound on the order of a solvable factor of every almost simple group and we determine the exact factorizations with a solvable factor. As an application, we describe the finite primitive permutation groups with a nilpotent regular subgroup, extending classical results of Burnside and Schur on cyclic regular subgroups, and more recent work of Li in the abelian case.
Original languageEnglish
Article number107499
Number of pages36
JournalAdvances in Mathematics
Early online date4 Dec 2020
Publication statusPublished - 22 Jan 2021


  • Almost simple groups
  • Factorizations
  • Primitive groups
  • Regular subgroups

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