可解CN-群与π-可分Cππ-群

G. Higman studied first the finite groups in which every element has prime power order except 1(see[1]),that is,the centralizer of every element is is a p-group except 1.Later manv authors have generalized it. On the one hand, the generalization is CN-groups, that is, the finite groups in which the centralizer of every element is nilpotent except 1(see[2,3]).On the other hand, the generalization is C22-groups, that is, the groups are of even order and the centralizer of any involution is a 2-group;a C22-group named again CIT-gro-     

幂群与它的生成群

设г是G上的幂群,即以G的非空子集为元素,在G的子集的运算之下所成的群.P_1,P_2是这样的两个性质 P_1:对任意g∈G,存g∈G,存在A∈г,使得g∈A. P_2:对任意A,B∈г,如果A≠B,则A∩B=φ. 本文得出了群G上的幂群г分别具有性质P_1或P_2的充要条件.     

幂群与序关系

设Ｇ为非ｍｏｎｏｉｄａｌ群，Ｅ是它的正规子集，满足Ｅ²＝Ｅ并且１_Ｇ∈／Ｅ．利用Ｅ作为正锥，可以在Ｇ上定义一个偏序，并且Ｇ成为一个偏序群．这样就可以利用这个序关系同时研究群Ｇ以及Ｇ上的以Ｅ为单位元的幂群．当Ｅ是极大子半群时，得到Ｇ的一个结构定理；在Ｇ是格序群的条件下，Ｇ上的幂群Γ可以膨胀为一个拟商群．