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math.RA2026
Weakly Sigma-cotorsion rings
Manuel Cortés-Izurdiaga, Sergio Estrada, José Manuel Fresneda
We study the class of rings for which every direct sum of injective -modules is cotorsion. We call them weakly -cotorsion rings. The defining property might be seen as t…
math.RA2026
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…