normal subgroup

• 不变子群,正规子群

normal subgroup的用法和样例：

例句

1. Congruences in semigroups are similar to normal subgroups in groups and ideals in rings.By congruencs, one can thoroughly obtain characterizations of E-inversive semigroups.
   摘要半群的同余类似于群中的正规子群或环中的理想，旨在对代数系统进行分类，以期得到关于半群的细致刻画。