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We construct a new cohomology theory for proper smooth (formal) schemes over the ring of integers of C_p. It takes values in a mixed-characteristic analogue of Dieudonne modules, which was previously defined by Fargues as a version of…

Algebraic Geometry · Mathematics 2019-01-16 Bhargav Bhatt , Matthew Morrow , Peter Scholze

In a preceding article the authors and Tran Ngoc Nam constructed a minimal injective resolution of the mod 2 cohomology of a Thom spectrum. A Segal conjecture type theorem for this spectrum was proved. In this paper one shows that the above…

Algebraic Topology · Mathematics 2016-11-25 Nguyen D. H. Hai , Lionel Schwartz

Our purpose in this work is multifold. First, we provide general criteria for the finiteness of the projective and injective dimensions of a finite module $M$ over a (commutative) Noetherian ring $R$. Second, in the other direction, we…

Commutative Algebra · Mathematics 2024-05-02 Souvik Dey , Rafael Holanda , Cleto B. Miranda-Neto

The study of rings and modules with homological criteria is a cornerstone of commutative algebra. Let $R$ be a commutative Noetherian ring with identity (not necessarily local) and $\frak a$ a proper ideal of $R$. In this paper, a relative…

Commutative Algebra · Mathematics 2023-08-22 Parisa Pourghobadian , Kamran Divaani-Aazar , Ahad Rahimi

Is the cohomology of the classifying space of a p-compact group, with Noetherian twisted coefficients, a Noetherian module? This note provides, over the ring of p-adic integers, such a generalization to p-compact groups of the Evens-Venkov…

Algebraic Topology · Mathematics 2015-03-26 Kasper K. S. Andersen , Natalia Castellana , Vincent Franjou , Alain Jeanneret , Jerome Scherer

We show that the well-known fact that the equivariant cohomology of a torus action is a torsion-free module if and only if the map induced by the inclusion of the fixed point set is injective generalises to actions of arbitrary compact…

Algebraic Topology · Mathematics 2012-03-02 Oliver Goertsches , Sönke Rollenske

Let $G$ be an algebraic group over a field $k$, and $M$ and $N$ be $G$-modules. In 1961, Hochschild showed how one can define the cohomology groups $\text{Ext}_{G}^{i}(M,N)$. Kimura, in 1965, showed that one can generalize this to get…

Group Theory · Mathematics 2026-02-05 Gabriel T. Loos

For a $C^{*}$-category with a strict $G$-action we construct examples of equivariant coarse homology theories. To this end we first introduce versions of Roe categories of objects in $C^{*}$-categories which are controlled over bornological…

K-Theory and Homology · Mathematics 2023-06-21 Ulrich Bunke , Alexander Engel

In this paper we study injective modules over universal enveloping algebras of finite-dimensional Lie algebras over fields of arbitrary characteristic. Most of our results are dealing with fields of prime characteristic but we also…

Representation Theory · Mathematics 2007-05-23 Joerg Feldvoss

Given a higher-rank graph $\Lambda$, we investigate the relationship between the cohomology of $\Lambda$ and the cohomology of the associated groupoid $G_\Lambda$. We define an exact functor between the abelian category of right modules…

Operator Algebras · Mathematics 2018-07-18 Elizabeth Gillaspy , Alexander Kumjian

We consider the homotopy category of complexes of projective modules over any gentle algebra. We prove that indecomposable $\Sigma$-pure-injective objects in s must be shifts of string or band complexes. We begin with a survey of purity in…

Representation Theory · Mathematics 2020-04-15 Raphael Bennett-Tennenhaus

In the paper I introduce a new characteristic class $c(E)$ for a finite rank vector bundle $E$ on an affine scheme $S:=Spec(A)$ - the fundamental class of $E$. The class $c(E)$ is not a characteristic class in the classical sense in the…

Algebraic Geometry · Mathematics 2025-04-22 Helge Øystein Maakestad

Inspired by a question raised by Eisenbud-Musta\c{t}\u{a}-Stillman regarding the injectivity of maps from ${\rm Ext}$ modules to local cohomology modules and the work by the third author with Pham, we introduce a class of rings which we…

Commutative Algebra · Mathematics 2019-01-09 Hailong Dao , Alessandro De Stefani , Linquan Ma

Let $H$ be a Hopf algebra. We consider $H$-equivariant modules over a Hopf module category $\mathcal C$ as modules over the smash extension $\mathcal C\# H$. We construct Grothendieck spectral sequences for the cohomologies as well as the…

Rings and Algebras · Mathematics 2020-09-16 Mamta Balodi , Abhishek Banerjee , Samarpita Ray

This paper deals with the notion of grade of ideals with respect to torsion theories defined via some homological tools such as Ext-modules, Koszul cohomology modules, \v{C}ech and local cohomology modules over commutative rings which are…

Commutative Algebra · Mathematics 2012-08-28 Mohsen Asgharzadeh , Massoud Tousi

We study Martsinkovsky-Russell torsion modules [MaRu20] with pure embeddings as an abstract elementary class. We give a model-theoretic characterization of the pure-injective and the $\Sigma$-pure-injective modules relative to the class of…

Logic · Mathematics 2023-02-24 Marcos Mazari-Armida

In this paper, we introduce and study the notion of linkage of modules by reflexive homomorphisms. This notion unifies and generalizes several known concepts of linkage of modules and enables us to study the theory of linkage of modules…

Commutative Algebra · Mathematics 2021-09-02 Fatemeh Dehghani-Zadeh , Mohammad-T. Dibaei , Arash Sadeghi

P. Aluffi introduced in [1] a new graded algebra in order to conveniently express characteristic cycles in the theory of singular varieties. This algebra is attached to a surjective ring homomorphism $A\surjects B$ by taking a suitable…

Commutative Algebra · Mathematics 2016-01-25 Zaqueu Ramos , Aron Simis

We prove some injectivity theorems. Our proof depends on the theory of mixed Hodge structures on cohomology groups with compact support. Our injectivity theorems would play crucial roles in the minimal model theory for higher-dimensional…

Algebraic Geometry · Mathematics 2015-07-06 Osamu Fujino

Baer's Criterion of injectivity implies that injectivity of a module is a factorization property w.r.t. a single monomorphism. Using the notion of a cotorsion pair, we study generalizations and dualizations of factorization properties in…

Rings and Algebras · Mathematics 2019-12-10 Jan Šaroch , Jan Trlifaj