Min-Flat Modules and Min-Coherent Rings

Let R be a ring. A left R-module M is said to be min-injective if for any simple left ideal I. A right R-module N is called min-flat if for any simple left ideal I. R is said to be a left min-coherent ring (left PS ring) in case every simple left ideal is finitely presented (projective). We characterize min-coherent rings, PS rings, and universally mininjective rings using min-injective and min-flat modules.