A NOTE ON ℵ0-INJECTIVE RINGS
Abstract
A ring R is called right ℵ0-injective if every homomorphism from a countably generated right ideal of R to RR can be extended to a homomorphism from RR to RR. In this note, some characterizations of ℵ0-injective rings are given. It is proved that if R is semilocal, then R is right ℵ0-injective if and only if every homomorphism from a countably generated small right ideal of R to RR can be extended to one from RR to RR. It is also shown that if R is right noetherian and left ℵ0-injective, then R is quasi-Frobenius. This result can be considered as an approach to the Faith–Menal conjecture.