摘要：

Let G be a permutation group on a finite set and let p be a prime. In this talk, we shall show that the largest class two p-quotient of G has order at most p^{n/p} (or 2^{3n/4} if p=2), where n is the number of points moved by a Sylow p-subgroup of G. We also describe the groups whose largest class two p-quotients can reach such  bound.  This extends earlier work of Kovács and Praeger from 1989.