有限群G的子群H称为在G中具有半覆盖-远离性质,若存在G的一个主群列1=G0〈G1〈…〈Gl=G,使得对每一i=1,…,l,或者H覆盖主因子Gj/Gj-1或者H远离Gj/Gj-1。该文利用Hall子群的半覆盖一远离性质,得到有限群可解和π-可解的若干充分及必要条件,推广了几个已知的定理,包括Schur—Zassenhaus定理。
A subgroup H of a finite group G is said to have the semi cover - avoidance property in a group G if there is a chief series 1 = G0 〈 G1 〈… 〈 Gl = G, such that for every i = 1,...,l, either H covers Gj/Gj-1 or H avoids Gj/ Gj- 1. By using the semi cover - avoidance properties of some Hall subgroups, we present several sufficient conditions for a finite group to be solvable and π - solvable. Our results generlize some known theorems, including Schur - Zassenhaus theorem.