Obstructions for deformations of complexes

Frauke M. Bleher; Ted Chinburg

Displaying similar documents to “Obstructions for deformations of complexes”

Finiteness Theorems for Deformations of Complexes

Frauke M. Bleher, Ted Chinburg (2013)

Annales de l’institut Fourier

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We consider deformations of bounded complexes of modules for a profinite group $G$ over a field of positive characteristic. We prove a finiteness theorem which provides some sufficient conditions for the versal deformation of such a complex to be represented by a complex of $G$ -modules that is strictly perfect over the associated versal deformation ring.

Lifting $D$ -modules from positive to zero characteristic

João Pedro P. dos Santos (2011)

Bulletin de la Société Mathématique de France

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We study liftings or deformations of $D$ -modules ( $D$ is the ring of differential operators from EGA IV) from positive characteristic to characteristic zero using ideas of Matzat and Berthelot’s theory of arithmetic $D$ -modules. We pay special attention to the growth of the differential Galois group of the liftings. We also apply formal deformation theory (following Schlessinger and Mazur) to analyze the space of all liftings of a given $D$ -module in positive characteristic. At the end we compare...

The correspondence between Barsotti-Tate groups and Kisin modules when $p = 2$

Tong Liu (2013)

Journal de Théorie des Nombres de Bordeaux

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Let $K$ be a finite extension over $ℚ_{2}$ and $𝒪_{K}$ the ring of integers. We prove the equivalence of categories between the category of Kisin modules of height 1 and the category of Barsotti-Tate groups over $𝒪_{K}$ .

A note on Frobenius divided modules in mixed characteristics

Pierre Berthelot (2012)

Bulletin de la Société Mathématique de France

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If $X$ is a smooth scheme over a perfect field of characteristic $p$ , and if $𝒟_{X}^{(\infty)}$ is the sheaf of differential operators on $X$ [7], it is well known that giving an action of $𝒟_{X}^{(\infty)}$ on an $𝒪_{X}$ -module $ℰ$ is equivalent to giving an infinite sequence of $𝒪_{X}$ -modules descending $ℰ$ via the iterates of the Frobenius endomorphism of $X$ [5]. We show that this result can be generalized to any infinitesimal deformation $f : X \to S$ of a smooth morphism in characteristic $p$ , endowed with Frobenius liftings. We also show that it...

Local cohomology, cofiniteness and homological functors of modules

Kamal Bahmanpour (2022)

Czechoslovak Mathematical Journal

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Let $I$ be an ideal of a commutative Noetherian ring $R$ . It is shown that the $R$ -modules $H_{I}^{j} (M)$ are $I$ -cofinite for all finitely generated $R$ -modules $M$ and all $j \in ℕ_{0}$ if and only if the $R$ -modules ${Ext}_{R}^{i} (N, H_{I}^{j} (M))$ and ${Tor}_{i}^{R} (N, H_{I}^{j} (M))$ are $I$ -cofinite for all finitely generated $R$ -modules $M$ , $N$ and all integers $i, j \in ℕ_{0}$ .

The Grothendieck ring of quantum double of quaternion group

Hua Sun, Jia Pang, Yanxi Shen (2024)

Czechoslovak Mathematical Journal

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Let $𝕜$ be an algebraically closed field of characteristic $p \neq 2$ , and let $Q_{8}$ be the quaternion group. We describe the structures of all simple modules over the quantum double $D (𝕜 Q_{8})$ of group algebra $𝕜 Q_{8}$ . Moreover, we investigate the tensor product decomposition rules of all simple $D (𝕜 Q_{8})$ -modules. Finally, we describe the Grothendieck ring $G_{0} (D (𝕜 Q_{8}))$ by generators with relations.

Recollements induced by good (co)silting dg-modules

Rongmin Zhu, Jiaqun Wei (2023)

Czechoslovak Mathematical Journal

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Let $U$ be a dg- $A$ -module, $B$ the endomorphism dg-algebra of $U$ . We know that if $U$ is a good silting object, then there exist a dg-algebra $C$ and a recollement among the derived categories $𝐃 (C, d)$ of $C$ , $𝐃 (B, d)$ of $B$ and $𝐃 (A, d)$ of $A$ . We investigate the condition under which the induced dg-algebra $C$ is weak nonpositive. In order to deal with both silting and cosilting dg-modules consistently, the notion of weak silting dg-modules is introduced. Thus, similar results for good cosilting dg-modules are obtained....

Annihilators of local homology modules

Shahram Rezaei (2019)

Czechoslovak Mathematical Journal

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Let $(R, 𝔪)$ be a local ring, $𝔞$ an ideal of $R$ and $M$ a nonzero Artinian $R$ -module of Noetherian dimension $n$ with $hd (𝔞, M) = n$ . We determine the annihilator of the top local homology module $H_{n}^{𝔞} (M)$ . In fact, we prove that ${Ann}_{R} (H_{n}^{𝔞} (M)) = {Ann}_{R} (N (𝔞, M)),$ where $N (𝔞, M)$ denotes the smallest submodule of $M$ such that $hd (𝔞, M / N (𝔞, M)) < n$ . As a consequence, it follows that for a complete local ring $(R, 𝔪)$ all associated primes of $H_{n}^{𝔞} (M)$ are minimal.

Irregularity of an analogue of the Gauss-Manin systems

Céline Roucairol (2006)

Bulletin de la Société Mathématique de France

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In $𝒟$ -modules theory, Gauss-Manin systems are defined by the direct image of the structure sheaf $𝒪$ by a morphism. A major theorem says that these systems have only regular singularities. This paper examines the irregularity of an analogue of the Gauss-Manin systems. It consists in the direct image complex $f_{+} (𝒪 e^{g})$ of a $𝒟$ -module twisted by the exponential of a polynomial $g$ by another polynomial $f$ , where $f$ and $g$ are two polynomials in two variables. The analogue of the Gauss-Manin systems can...

On the minimaxness and coatomicness of local cohomology modules

Marzieh Hatamkhani, Hajar Roshan-Shekalgourabi (2022)

Czechoslovak Mathematical Journal

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Let $R$ be a commutative Noetherian ring, $I$ an ideal of $R$ and $M$ an $R$ -module. We wish to investigate the relation between vanishing, finiteness, Artinianness, minimaxness and $𝒞$ -minimaxness of local cohomology modules. We show that if $M$ is a minimax $R$ -module, then the local-global principle is valid for minimaxness of local cohomology modules. This implies that if $n$ is a nonnegative integer such that ${(H_{I}^{i} (M))}_{𝔪}$ is a minimax $R_{𝔪}$ -module for all $𝔪 \in Max (R)$ and for all $i < n$ , then the set ${Ass}_{R} (H_{I}^{n} (M))$ is finite. Also, if $H_{I}^{i} (M)$ is...

Cofiniteness and finiteness of local cohomology modules over regular local rings

Jafar A&#039;zami, Naser Pourreza (2017)

Czechoslovak Mathematical Journal

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Let $(R, 𝔪)$ be a commutative Noetherian regular local ring of dimension $d$ and $I$ be a proper ideal of $R$ such that ${mAss}_{R} (R / I) = {Assh}_{R} (I)$ . It is shown that the $R$ -module $H_{I}^{ht (I)} (R)$ is $I$ -cofinite if and only if $cd (I, R) = ht (I)$ . Also we present a sufficient condition under which this condition the $R$ -module $H_{I}^{i} (R)$ is finitely generated if and only if it vanishes.

Special modules for $R (PSL (2, q))$

Liufeng Cao, Huixiang Chen (2023)

Czechoslovak Mathematical Journal

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Let $R$ be a fusion ring and $R_{ℂ} : = R \otimes_{ℤ} ℂ$ be the corresponding fusion algebra. We first show that the algebra $R_{ℂ}$ has only one left (right, two-sided) cell and the corresponding left (right, two-sided) cell module. Then we prove that, up to isomorphism, $R_{ℂ}$ admits a unique special module, which is 1-dimensional and given by the Frobenius-Perron homomorphism FPdim. Moreover, as an example, we explicitly determine the special module of the interpolated fusion algebra $R (PSL (2, q)) : = r (PSL (2, q)) \otimes_{ℤ} ℂ$ up to isomorphism, where $r (PSL (2, q))$ is the...

Real deformations and invariants of map-germs

J. H. Rieger, M. A. S. Ruas, R. Wik Atique (2008)

Banach Center Publications

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A stable deformation $f^{t}$ of a real map-germ $f : ℝ ⁿ, 0 \to ℝ^{p}, 0$ is said to be an M-deformation if all isolated stable (local and multi-local) singularities of its complexification $f_{ℂ}^{t}$ are real. A related notion is that of a good real perturbation $f^{t}$ of f (studied e.g. by Mond and his coworkers) for which the homology of the image (for n < p) or discriminant (for n ≥ p) of $f^{t}$ coincides with that of $f_{C}^{t}$ . The class of map germs having an M-deformation is, in some sense, much larger than the one having a good...

Relative tilting modules with respect to a semidualizing module

Maryam Salimi (2019)

Czechoslovak Mathematical Journal

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Let $R$ be a commutative Noetherian ring, and let $C$ be a semidualizing $R$ -module. The notion of $C$ -tilting $R$ -modules is introduced as the relative setting of the notion of tilting $R$ -modules with respect to $C$ . Some properties of tilting and $C$ -tilting modules and the relations between them are mentioned. It is shown that every finitely generated $C$ -tilting $R$ -module is $C$ -projective. Finally, we investigate some kernel subcategories related to $C$ -tilting modules.

Derived endo-discrete artin algebras

Raymundo Bautista (2006)

Colloquium Mathematicae

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Let Λ be an artin algebra. We prove that for each sequence ${(h_{i})}_{i \in ℤ}$ of non-negative integers there are only a finite number of isomorphism classes of indecomposables $X \in^{b} (Λ)$ , the bounded derived category of Λ, with $l e n g t h_{E (X)} H^{i} (X) = h_{i}$ for all i ∈ ℤ and E(X) the endomorphism ring of X in $^{b} (Λ)$ if and only if $^{b} (M o d Λ)$ , the bounded derived category of the category $M o d Λ$ of all left Λ-modules, has no generic objects in the sense of [4].

Cominimaxness of local cohomology modules

Moharram Aghapournahr (2019)

Czechoslovak Mathematical Journal

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Let $R$ be a commutative Noetherian ring, $I$ an ideal of $R$ . Let $t \in ℕ_{0}$ be an integer and $M$ an $R$ -module such that ${Ext}_{R}^{i} (R / I, M)$ is minimax for all $i \leq t + 1$ . We prove that if $H_{I}^{i} (M)$ is ${FD}_{\leq 1}$ (or weakly Laskerian) for all $i < t$ , then the $R$ -modules $H_{I}^{i} (M)$ are $I$ -cominimax for all $i < t$ and ${Ext}_{R}^{i} (R / I, H_{I}^{t} (M))$ is minimax for $i = 0, 1$ . Let $N$ be a finitely generated $R$ -module. We prove that ${Ext}_{R}^{j} (N, H_{I}^{i} (M))$ and ${Tor}_{j}^{R} (N, H_{I}^{i} (M))$ are $I$ -cominimax for all $i$ and $j$ whenever $M$ is minimax and $H_{I}^{i} (M)$ is ${FD}_{\leq 1}$ (or weakly Laskerian) for all $i$ .

Models of group schemes of roots of unity

A. Mézard, M. Romagny, D. Tossici (2013)

Annales de l’institut Fourier

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Let $𝒪_{K}$ be a discrete valuation ring of mixed characteristics $(0, p)$ , with residue field $k$ . Using work of Sekiguchi and Suwa, we construct some finite flat $𝒪_{K}$ -models of the group scheme $μ_{p^{n}, K}$ of $p^{n}$ -th roots of unity, which we call . We carefully set out the general framework and algebraic properties of this construction. When $k$ is perfect and $𝒪_{K}$ is a complete totally ramified extension of the ring of Witt vectors $W (k)$ , we provide a parallel study of the Breuil-Kisin modules of finite flat models of $μ_{p^{n}, K}$ ,...