CO-EPI-RETRACTABLE MODULES AND CO-PRI RINGS

A module M is called co-epi-retractable if it contains a copy of each of its factor modules. It is proved that a ring R is co-pri (i.e., R-R is co-epi-retractable) and reduced if and only if R is a finite product of division rings. We show that a commutative ring is co-pri if and only if it is a finite product of special rings. Duality-like connections are established for epi-retractable and co-epi-retractable modules. It is shown that if R is a pli ring and R-R is self-cogenerator, then R is co-pri.