摘要
利用Ｋｕｒǒｓ关于二秩无扭Ａｂｅｌ群的不变量理论和二元二次不定方程，给出了二秩无扭Ａｂｅｌ群的子群均为特征子群的充分必要条件．
On the basis of Kurǒs' complete system of invariants for torsion free groups and diaphantine equations,this paper investigates the structures of torsion free groups of rank 2 and in which all their subgroups are characteristic ones,also it gives necessary and sufficient conditions for these groups relative to their parameters.
基金
浙江省自然科学基金
关键词
子群
无扭Abel群
特征子群
ABEL群
type of group
Kurǒs' complete system of invariants
quadratic algebraic number
diaphantine equation
