Singular compactness and definability for -cotorsion and Gorenstein modules

J Šaroch, J Št'ovíček - Selecta Mathematica, 2020 - Springer
We introduce a general version of the singular compactness theorem which makes it
possible to show that being a Σ Σ-cotorsion module is a property of the complete theory of …

Gorenstein weak global dimension is symmetric

LW Christensen, S Estrada… - Mathematische …, 2021 - Wiley Online Library
We study the Gorenstein weak global dimension of associative rings and its relation to the
Gorenstein global dimension. In particular, we prove the conjecture that the Gorenstein …

Flat quasi-coherent sheaves as direct limits, and quasi-coherent cotorsion periodicity

L Positselski, J Stovicek - arXiv preprint arXiv:2212.09639, 2022 - arxiv.org
We show that every flat quasi-coherent sheaf on a quasi-compact quasi-separated scheme
is a directed colimit of locally countably presentable flat quasi-coherent sheaves. More …

Model structures and relative Gorenstein flat modules and chain complexes

S Estrada, A Iacob, MA Pérez - Categorical, homological and …, 2020 - books.google.com
A recent result by J. Šaroch and J. Šťovíček asserts that there is a unique abelian model
structure on the category of left R-modules, for any associative ring R with identity, whose …

Flat comodules and contramodules as directed colimits, and cotorsion periodicity

L Positselski - arXiv preprint arXiv:2306.02734, 2023 - arxiv.org
This paper is a follow-up to arXiv: 2212.09639. We consider two algebraic settings of
comodules over a coring and contramodules over a topological ring with a countable base …

[PDF][PDF] Derived category methods in commutative algebra

LW Christensen, HB Foxby, H Holm - preprint, 2012 - math.ttu.edu
Homological algebra originated in late 19th century topology. Homological studies of
algebraic objects, such as rings and modules, only got under way in the middle of the 20th …

Fp-projective periodicity

S Bazzoni, M Hrbek, L Positselski - Journal of Pure and Applied Algebra, 2024 - Elsevier
The phenomenon of periodicity, discovered by Benson and Goodearl, is linked to the
behavior of the objects of cocycles in acyclic complexes. It is known that any flat Proj …

A refinement of Gorenstein flat dimension via the flat–cotorsion theory

LW Christensen, S Estrada, L Liang, P Thompson… - Journal of Algebra, 2021 - Elsevier
We introduce a refinement of the Gorenstein flat dimension for complexes over an
associative ring—the Gorenstein flat-cotorsion dimension—and prove that it, unlike the …

Homotopy categories of totally acyclic complexes with applications to the flat-cotorsion theory

LW Christensen, S Estrada… - … combinatorial methods in …, 2020 - books.google.com
We introduce a notion of total acyclicity associated to a subcategory of an abelian category
and consider the Gorenstein objects they define. These Gorenstein objects form a Frobenius …

Locally coherent exact categories

L Positselski - arXiv preprint arXiv:2311.02418, 2023 - arxiv.org
A locally coherent exact category is a finitely accessible additive category endowed with an
exact structure in which the admissible short exact sequences are the directed colimits of the …