On extensions of an elementary abelian group of order by
If ℱ is a class of groups, then a minimal non-ℱ-group (a dual minimal non-ℱ-group resp.) is a group which is not in ℱ but any of its proper subgroups (factor groups resp.) is in ℱ. In many problems of classification of groups it is sometimes useful to know structure properties of classes of minimal non-ℱ-groups and dual minimal non-ℱ-groups. In fact, the literature on group theory contains many results directed to classify some of the most remarkable among the aforesaid classes. In particular, V....
Let be a finite group. The prime graph of is a graph whose vertex set is the set of prime divisors of and two distinct primes and are joined by an edge, whenever contains an element of order . The prime graph of is denoted by . It is proved that some finite groups are uniquely determined by their prime graph. In this paper, we show that if is a finite group such that , where , then has a unique nonabelian composition factor isomorphic to or .
Let be a finite group. The prime graph of is a simple graph whose vertex set is and two distinct vertices and are joined by an edge if and only if has an element of order . A group is called -recognizable by prime graph if there exist exactly nonisomorphic groups satisfying the condition . A 1-recognizable group is usually called a recognizable group. In this problem, it was proved that is recognizable, if is an odd prime and is odd. But for even , only the recognizability...