摘要

For a positive integer t, a finite p-group G is an At-group if all subgroups of index p(t) in G are abelian, and at least one subgroup of index p(t-1) in G is not abelian. An A(t)-group G satisfies a chain condition if every A(i)-subgroup of G is contained in an A(i+1)-subgroup for all i is an element of {0, 1, 2,..., t - 1}, where A(0)-subgroups denote abelian subgroups. We prove that if t >= 2, then, except for some p-groups of small order, the following conditions for a group G of order p(n) are equivalent: (1) G is an A(t)-group satisfying a chain condition; (2) every subgroup of order p(n-k) in G is an A(t-k)-subgroup for 0 <= k <= t; (3) G is an ordinary metacyclic group.