徐卫东,沈如林.关于循环子群数目超过一半的几乎单群[J].井冈山大学自然版,2024,45(2):7-11 |
关于循环子群数目超过一半的几乎单群 |
ALMOST SIMPLE GROUPS WITH MORE THAN HALF NUMBER OF CYCLIC SUBGROUPS |
投稿时间:2023-08-13 修订日期:2023-11-02 |
DOI:10.3969/j.issn.1674-8085.2024.02.002 |
中文关键词: 有限群 几乎单群 循环子群个数 |
英文关键词: finite groups almost simple groups number of cyclic subgroups |
基金项目:国家自然科学基金项目(12161035) |
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中文摘要: |
假设G为有限群,记c(G)为群G的循环子群个数,α(G)为群G的循环子群个数与群阶数的比值,即α(G):=c(G)/|G|。本次研究证明了若G为几乎单群,即S ≤ G ≤ Aut(S),这里S为有限非交换单群,则α(G)≥ 1/2当且仅当G≅A5,S5,S6。 |
英文摘要: |
Let G be a finite group,c(G) be the number of cyclic subgroups of G ,and α(G) be the ratio of the number of cyclic subgroups of G to the order of the group,i.e.α(G):c(G)/|G|.In this paper,it proves that if G is an almost simple group,i.e.S ≤ G ≤ Aut(S),in which S is a finite non-abelian simple group,then α(G) ≥ 1/2 if and only if G ≅ A5,S5,S6. |
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