Strongly Duo Modules and Rings

Abstract

An R-module M is called strongly duo if Tr(N, M) = N for every N ≤ M R . Several equivalent conditions to being strongly duo are given. If M R is strongly duo and reduced, then End R (M) is a strongly regular ring and the converse is true when R is a Dedekind domain and M R is torsion. Over certain rings, nonsingular strongly duo modules are precisely regular duo modules. If R is a Dedekind domain, then M R is strongly duo if and only if either M ≈ R or M R is torsion and duo. Over a commutative ring, strongly duo modules are precisely pq-injective duo modules and every projective strongly duo module is a multiplication module. A ring R is called right strongly duo if R R is strongly duo. Strongly regular rings are precisely reduced (right) strongly duo rings. A ring R is Noetherian and all of its factor rings are right strongly duo if and only if R is a serial Artinian right duo ring.