证明
Lemma 3 ([Labels]). Suppose that [D,X] is fenced, and put F_X=core_X(D) =⋂_ g∈X…Lemma 63. Let T be a finite nonabelian simple group and let Inn(T)≤H(T) . Every…观点
Lemma 3 ([Labels]) would give a nonabelian simple composition factor of the soluble top group. For the second assertion, quotient by Inn(T) , which is contained in the bottom B . The resulting interval lies in the soluble group Out(T) , by Schreier's Theorem.