A right $ R $-module $ M $ is called $ R $-projective provided that it is projective relative to
the right $ R $-module $ R_ {R} $. This paper deals with the rings whose all nonsingular …

In the class of all exact torsion theories the torsionfree classes are cover (pre-cover) classes
if and only if the classes of torsionfree relatively injective modules or relatively exact …

Abstract A right R-module M is called R-projective provided that it is projective relative to the
right R-module R R. One of the parts of this thesis deals with the rings whose all nonsingular …

One of the results in my previous paper {\it On torsionfree classes which are not precover
classes\/}, preprint, Corollary 3, states that for every hereditary torsion theory $\tau $ for the …

Let $ G $ be a multiplicative monoid. If $ RG $ is a non-singular ring such that the class of all
non-singular $ RG $-modules is a cover class, then the class of all non-singular $ R …

We shall introduce the class of strongly cancellative multiplicative monoids which contains
the class of all totally ordered cancellative monoids and it is contained in the class of all …