… , and cotorsion functors. Using the existence of envelopes and covers of these functors, we
give some … In addition, we will deal with properties of functors on the stable category of finitely …

… covers exist in the category of topological spaces. Algebraic closures of fields are envelopes
in the category … If T is covariant we get the right derived functors and if T is contravariant we …

… orthogonal classes and balanced functors in the category of … some results about functors
which preserve or reflect covers. … various covers and envelopes with respect to the classes of …

… envelopes in general category theory, and under which conditions they exist and are functors…
Let F be a covariant functor (the case of a contravariant functor is considered similarly). If (i) …

… to the structure of particular classes of modules. Covers and envelopes are unique, so they
… ) if for each finitely presented module F, the functor Hom(F,−) preserves exactness of the …

… denotes the full subcategory of the category of … category of additive functors from Pf{R) to
Abelian groups, we have the following characterisation of the injective objects in this category. …

… our theorem we develop certain new methods for relating triangulated categories to their (…
define certain R-linear cohomological functors FY C from C to R − mod for C ∈ I. In the case …

… Simultaneously, they asserted that every functor in (mod… covers and envelopes theory in
some functor categories. It is showed that every functor in (mod-R, Ab) has an FP-injective cover …

… covered in this paper are the relation between semi-functors … Although we will see that
semi-functors between categories … this paper uses the Karoubi envelope construction to translate …

… covers exist in the category of topological spaces. Algebraic closures of elds are envelopes
in the category of … If T is covariant we get the right derived functors and if T is contravariant we …