讨论群的阶与群的不可约特征标个数的商和群的结构之间的关系,定义μ(G)=|G|/|Irr(G)|.得到了 定理1 若G是非交换有限群,μ(G)=2。则cd(G)={1,2},|G|=3,且|G|=6|Irr|(G)|,其中Irr1(G)表示G的所有非线性不可约特征标. 定理2 对非交换有限群G有 (1)设P为|G|的最小素因子,设cd(G)={1,m1,m2,…,m4},1〈m1〈m2〈…〈md,则μ(G)≥pmi^2/(mi^2+p-1)等号成立当且仅当d=1且|G’|=P. (2)若|G/G'|=1,则μ(G)≥12,且μ(G)=12当且仅当G≈A5。 (3)若|G/G'|=2,则≈(G)≥2,且≈(G)=2当且仅当G≈S3.
The relation of the quotient of the order of a finite group G and | Irr(G) | with the structure of G are discussed. Letμ(G) = | G | /| rr(G) |. The following theorems are obtained. Theorem 1 Let G be non-abelian finite group withμ(G) = 2, then cd(G) = { 1, 2 }, | G' | = 3, and | G | = 61|Irr1(G)|. Theorem 2 Let G be non-abelian finite group, then (1) Supposep be smallest prime divisor of | G | , cd(G) = {1, m1, m2, …, md then μ(G)≥pmi^2/(mi^2+p-1),μ(G)=pmi^2/(mi^2+p-1) if and only if d=1 and |G'|=p (2)if |G/G'|=1,then μ(G)≥12,and μ(G)=12 if and only if G≈A5. (3)if |G/G'|=2,then μ(G)≥2,and μ(G)=2 if and only if G≈S3.