摘要 : Let h(Γ) denote the number of distinct finite groups G such that π_e (G) =Γ. Here Γ is a set of positive integers, and π_e (G) is the set of element orders of G. It is proved that h (Γ) ∈ {0, 1, ∞} for Γis contained in {1, 2, 3, .... 展开 Let h(Γ) denote the number of distinct finite groups G such that π_e (G) =Γ. Here Γ is a set of positive integers, and π_e (G) is the set of element orders of G. It is proved that h (Γ) ∈ {0, 1, ∞} for Γis contained in {1, 2, 3, ...., 20} 收起