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arXiv 2409.01043math.GR
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关于单置换群中的错排

On derangements in simple permutation groups

Timothy C. Burness, Marco Fusari

AI总结:

本文研究了有限单置换群中的错排问题,推广了已有关于错排比例下界与平方覆盖的结论,证明了具有可溶点稳定子的本原单群的最佳下界,并得出任意有限单传递群均可由两个共轭错排生成。

摘要:

设 $G \leqslant {\rm Sym}(Ω)$ 为有限传递置换群,回顾 $G$ 中的元素若在 $Ω$ 上没有固定点则为错排。设 $Δ(G)$ 为 $G$ 中错排的集合,定义 $δ(G) = |Δ(G)|/|G|$ 以及 $Δ(G)^2 = \{ xy \\,:\\, x,y \in Δ(G)\}$。近年来,单群中错排的研究备受关注,并取得了若干显著成果。例如,结合 Fulman 和 Guralnick 的定理与 Larsen、Shalev 和 Tiep 的近期工作,可得对于所有足够大的单传递群 $G$,有 $δ(G) \geqslant 0.016$ 且 $G = Δ(G)^2$。本文将这些结果在多个方向上进行了推广。例如,我们证明了对于所有具有可解点稳定子的有限本原单群,在无任何阶假设的情况下,$δ(G) \geqslant 89/325$ 且 $G = Δ(G)^2$ 成立,并证明了所给关于 $δ(G)$ 的下界是最佳的。我们还证明了每个有限单传递群均可由两个共轭的错排生成,并提出了关于任意本原置换群中错排的若干新结果。

英文摘要:

Let $G \leqslant {\rm Sym}(Ω)$ be a finite transitive permutation group and recall that an element in $G$ is a derangement if it has no fixed points on $Ω$. Let $Δ(G)$ be the set of derangements in $G$ and define $δ(G) = |Δ(G)|/|G|$ and $Δ(G)^2 = \{ xy \,:\, x,y \in Δ(G)\}$. In recent years, there has been a focus on studying derangements in simple groups, leading to several remarkable results. For example, by combining a theorem of Fulman and Guralnick with recent work by Larsen, Shalev and Tiep, it follows that $δ(G) \geqslant 0.016$ and $G = Δ(G)^2$ for all sufficiently large simple transitive groups $G$. In this paper, we extend these results in several directions. For example, we prove that $δ(G) \geqslant 89/325$ and $G = Δ(G)^2$ for all finite simple primitive groups with soluble point stabilisers, without any order assumptions, and we show that the given lower bound on $δ(G)$ is best possible. We also prove that every finite simple transitive group can be generated by two conjugate derangements, and we present several new results on derangements in arbitrary primitive permutation groups.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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