A comparation of the structure of two ring classes co – and PF

Abstract

In this paper, we compare the structure of two ring classes co-H and PF, both of them are extensions of the QF rings. Motivated by this comparision, we proved that "A ring R is QF if and only if R is right co-H and satisfying  or ;  if and only if R is right co-H and right or left Kasch".