We consider an arbitrary Abelian category A and a subcategory T closed under extensions
and direct summands, and characterize those T that are (semi-) special preenveloping in A; …

Given a noetherian abelian k-category of finite homological dimension, with a tilting object T
of projective dimension 2, the abelian category and the abelian category of modules over …

We relate the theory of envelopes and covers to tilting and cotilting theory, for (infinitely
generated) modules over arbitrary rings. Our main result characterizes tilting torsion classes …

To a big-tilting object in a complete, cocomplete abelian category with an injective
cogenerator we assign a big-cotilting object in a complete, cocomplete abelian category with …

For four wide classes of topological rings R, we show that all flat left R-contramodules have
projective covers if and only if all flat left R-contramodules are projective if and only if all left …

In [R. Colpi, KR Fuller, Tilting objects in abelian categories and quasitilted rings, Trans.
Amer. Math. Soc., in press] tilting objects in an arbitrary abelian category H are introduced …

We prove general results about completeness of cotorsion theories and existence of covers
and envelopes in locally presentable abelian categories, extending the well-established …

We show that a direct limit of projective contramodules (over a right linear topological ring) is
projective if it has a projective cover. A similar result is obtained for-strictly flat contramodules …

Let M be a module over an associative ring R and σ [M] the category of M-subgenerated
modules. Generalizing the notion of a projective generator in σ [M], a module P∈ σ [M] is …

We present applications of contramodule techniques to the Enochs conjecture about covers
and direct limits, both in the categorical tilting context and beyond. In the n-tilting–cotilting …