S. Estrada

activity

20242026

collaborators

6 papers

math.RA2026

Weakly Sigma-cotorsion rings

Manuel Cortés-Izurdiaga, Sergio Estrada, José Manuel Fresneda

We study the class of rings $R$ for which every direct sum of injective $R$ -modules is cotorsion. We call them weakly $Σ$ -cotorsion rings. The defining property might be seen as th…

math.RA2025

Acyclic complexes and regular rings

Lars Winther Christensen, Sergio Estrada, Peder Thompson

A 2009 paper by Iacob and Iyengar characterizes noetherian regular rings in terms of properties of complexes of projective modules, flat modules, and injective modules. We show tha…

math.CT2025

Gorenstein categories relative to G-admissible triples

Sergio Estrada, Octavio Mendoza, Marco A. Pérez

We present the notion of Gorenstein categories relative to G-admissible triples. This is a relativization of the concept of Gorenstein category (an abelian category with enough pro…

math.CT2024

Powers of ghost ideals

S. Estrada, X. H. Fu, I. Herzog +1

A theory of ordinal powers of the ideal $g_{S}$ of $S$ -ghost morphisms is developed by introducing for every ordinal $λ$ , the $λ$ -th inductive power…

math.CT2024

Transfer of homological objects in exact categories via adjoint triples. Applications to functor categories

Sergio Estrada, Manuel Cortés-Izurdiaga, Sinem Odabasi

For a given family ${(q_{i}, t_{i}, p_{i})}_{i \in I}$ of adjoint triples between exact categories $C$ or $D$ , we show that any cotorsio…

math.RA2024

Homotopy equivalences and Grothendieck duality over rings with finite Gorenstein weak global dimension

Junpeng Wang, Sergio Estrada

Let $R$ be a ring with Gwgldim $(R) < \infty$ . We obtain a triangle-equivalence $K (R - GProj) ≃ K (R - GInj)$ which restricts to a tri…