2.Considering the subnormal subgroups,some equivalent conditions for nilpotency of finite groups are given and a sufficient condition for nilpotency of finite groups is obtained.
2.Categories. Types or subgroups. An everyday encounter with categories is types of food, fruits, vegetables, carbohydrates, proteins, and so on. These are food categories.
3.They took over niches that had been left vacant by the Great Dying, and radiated across Pangea, onto every modern continent, into a host of subgroups.