A right module M over a ring R is said to be retractable if Hom R (M, N)≠ 0 for each nonzero
submodule N of M. We show that M⊗ R RG is a retractable RG-module if and only if MR is …

Abstract Baer's Criterion for Injectivity is a useful tool of the theory of modules. Its dual
version (DBC) is known to hold for all right perfect rings, but its validity for the non-right …

We apply set-theoretic methods to study projective modules and their generalizations over
transfinite extensions of simple artinian rings R. We prove that if R is small, then the Weak …

We will study commuting properties of the defect functor Def ß= Coker Hom C (ß,-)
Def_β=CokerHom_C(β,-) associate to a homomorphism ß in a finitely presented category …

Commentationes Mathematicae Universitatis Carolinae Page 1 Commentationes Mathematicae
Universitatis Carolinae Peter Kálnai; Jan Žemlička Products of small modules Commentationes …