The graded version of Goldie's Theorem

Extending ring derivations to right and symmetric rings and modules of quotients

We define and study the symmetric version of differential torsion theories. We prove that the symmetric versions of some of the existing results on derivations on right modules of quotients hold for derivations on symmetric modules of quotients. In particular, we prove that the symmetric Lambek, Goldie and perfect torsion theories are differential. We also study conditions under which a derivation on a right or symmetric module of quotients extends to a right or symmetric module of quotients with respect to a larger torsion theory. Using these results, we study extensions of ring derivations t…

关于分次拟-Cartan对与扭Steinberg代数

On Graded Quasi-Cartan Pairs and Twisted Steinberg Algebras

本文引入分次拟-Cartan、Cartan和对角子代数版本，证明了其与分次扭Steinberg代数的对应关系及分次离散扭曲的唯一性，推广了包含离散群代数的未分次结果。

Auslander's Theorem for group coactions on noetherian graded down-up algebras

We prove a version of a theorem of Auslander for finite group coactions on noetherian graded down-up algebras.

分次环的分次消去性质与分次单位正则Leavitt路代数

Graded cancellation properties of graded rings and graded unit-regular Leavitt path algebras

本文研究环的分次性质推广问题，提出消去、内部消去、替换和模论直接有限性的分次版本，并给出有限图E的Leavitt路代数分次单位正则的图论等价条件，揭示该性质对到达圈的路长的关键依赖及其受限性。

G-Graded Central Polynomials and G-Graded Posner's Theorem

Let F be characteristic zero field, G a residually finite group and W a G-prime and PI F-algebra. By constructing G-graded central polynomials for W, we prove the G-graded version of Posner's theorem. More precisely, if S denotes all non-zero degree e central elements of W, the algebra S^{-1}W is G-graded simple and finite dimensional over its center. Furthermore, we show how to use this theorem in order to recapture the result of Aljadeff and Haile stating that two G-simple algebras of finite dimension are isomorphix iff their ideals of graded identities coincide.

Rigidity of Graded Regular Algebras

We prove a graded version of Alev-Polo's rigidity theorem: the homogenization of the universal enveloping algebra of a semisimple Lie algebra and the Rees ring of the Weyl algebras $A_n(k)$ cannot be isomorphic to their fixed subring under any finite group action. We also show the same result for other classes of graded regular algebras including the Sklyanin algebras.

阶化李代数的泛包络

Universal enveloping of a graded Lie algebra

本文构造了非阿贝尔群阶化下的李代数阶化泛包络代数，证明其存在唯一性，推导了Witt定理与Ado定理的阶化版本，并探讨了李阶化与阿贝尔阶化的等价性问题。

分次与非单位环的消去性质：分次clean与分次exchange Leavitt路径代数

Cancellation properties of graded and nonunital rings. Graded clean and graded exchange Leavitt path algebras

本文将单位环的消去相关性质推广到非单位环和分次环，研究分次clean与分次exchange在分次矩阵环下的行为，并刻画Leavitt路径代数为分次clean或分次exchange的图论条件。

Graded Steinberg algebras and partial actions

Given a graded ample Hausdorff groupoid, we realise its graded Steinberg algebra as a partial skew inverse semigroup ring. We use this to show that for a partial action of a discrete group on a locally compact Hausdorff topological space, the Steinberg algebra of the associated groupoid is graded isomorphic to the corresponding partial skew group ring. We show that there is a one-to-one correspondence between the open invariant subsets of the topological space and the graded ideals of the partial skew group ring. We also consider the algebraic version of the partial $C^{*}$-algebra of an abeli…

Twists of graded Poisson algebras and related properties

We introduce a Poisson version of the graded twist of a graded associative algebra and prove that every graded Poisson structure on a connected graded polynomial ring $A:=\Bbbk[x_1,\ldots,x_n]$ is a graded twist of a unimodular Poisson structure on $A$, namely, if $π$ is a graded Poisson structure on $A$, then $π$ has a decomposition $$π=π_{unim} +\frac{1}{\sum_{i=1}^n {\rm deg} x_i} E\wedge {\mathbf m}$$ where $E$ is the Euler derivation, $π_{unim}$ is the unimodular graded Poisson structure on $A$ corresponding to $π$, and ${\mathbf m}$ is the modular derivation of $(A,π)$. This result is a …

Object-unital groupoid graded modules

In a previous article (see \cite{CNP}), we introduced and analyzed ring-theoretic properties of object unital $\mathcal{G}$-graded rings $R$, where $\mathcal{G}$ is a groupoid. In the present article, we analyze the category $\grmod$ of unitary $\G$-graded modules over such rings. Following ideas developed earlier by one of the authors in \cite{lundstrom2004}, we analyze the forgetful functor $U \colon \grmod \to \rmod$ and aim to determine properties $\mathcal{P}$ for which the following implications are valid for modules $M$ in $\grmod$: $M$ is $\mathcal{P}$ $\Rightarrow$ $U(M)$ is $\mathcal…

Noncommutative Auslander theorem

A version of Auslander theorem is proven for the following classes of noncommutative algebras: (a) noetherian PI local (or connected graded) algebras of finite injective dimension, (b) universal enveloping algebras of finite dimensional Lie algebras, and (c) noetherian graded down-up algebras.

Skew graded $(A_\infty)$ hypersurface singularities

For a skew version of a graded $(A_\infty)$ hypersurface singularity $A$, we study the stable category of graded maximal Cohen-Macaulay modules over $A$. As a consequence, we see that $A$ has countably infinite Cohen-Macaulay representation type and is not a noncommutative graded isolated singularity.

群分次自同态代数与Morita等价

Group graded endomorphism algebras and Morita equivalences

本文证明了特征三元组蝴蝶定理的群分次Morita等价版本，从而提供了一种从相关等价构造块扩张等价的新方法。

群体学分级半单环

Groupoid Graded Semisimple Rings

本文研究群体学分级半单环的理论，提出Γ₀-artinian概念，并证明了Wedderburn-Artin定理的群体学分级版本，同时探讨了群体学分级环的自由性及与半单范畴的关系。

Coabelian ideals in $\mathbb{N}$-graded Lie algebras and applications to right angled Artin Lie algebras

We consider homological finiteness properties $FP_n$ of certain $\mathbb{N}$-graded Lie algebras. After proving some general results, see Theorem A, Corollary B and Corollary C, we concentrate on a family that can be considered as the Lie algebra version of the generalized Bestvina-Brady groups associated to a graph $Γ$. We prove that the homological finiteness properties of these Lie algebras can be determined in terms of the graph in the same way as in the group case. In the last version we have corrected some missprints, in particular the statement of Theorem D (from $n-1$-acyclicity to $n-…

Ext vanishing and infinite Auslander-Buchsbaum

A vanishing theorem is proved for Ext groups over non-commutative graded algebras. Along the way, an "infinite" version is proved of the non-commutative Auslander-Buchsbaum theorem.

关于由消去单子分级的半赫瑞德环

On monoid graded semihereditary rings

研究分级左赫瑞德和左半赫瑞德环的模块性质，提供分级自由、投射、注入和平坦模块的分级版本，包括巴尔准则和拉兹洛定理。

Koszul differential graded algebras and BGG correspondence

The concept of Koszul differential graded algebra (Koszul DG algebra) is introduced. Koszul DG algebras exist extensively, and have nice properties similar to the classic Koszul algebras. A DG version of the Koszul duality is proved. When the Koszul DG algebra $A$ is AS-regular, the Ext-algebra $E$ of $A$ is Frobenius. In this case, similar to the classical BGG correspondence, there is an equivalence between the stable category of finitely generated left $E$-modules, and the quotient triangulated category of the full triangulated subcategory of the derived category of right DG $A$-modules cons…

McKay Correspondence for semisimple Hopf actions on regular graded algebras, I

In establishing a more general version of the McKay correspondence, we prove Auslander's theorem for actions of semisimple Hopf algebras H on noncommutative Artin-Schelter regular algebras A of global dimension two, where A is a graded H-module algebra, and the Hopf action on A is inner faithful with trivial homological determinant. We also show that each fixed ring A^H under such an action arises an analogue of a coordinate ring of a Kleinian singularity.

On commutative differential graded algebras

In this paper we undertake a basic study on connective commutative differential graded algebras (CDGA), more precisely, piecewise Noetherian CDGA, which is a DG-counter part of commutative Noetherian algebra. We establish basic results for example, Auslaner-Buchsbaum formula and Bass formula without any unnecessary assumptions. The key notion is the sup-projective (sppj) and inf-injective (ifij) resolutions introduced by the author, which are DG-versions of the projective and injective resolution for ordinary modules. These are different from DG-projective and DG-injective resolutions which is…

带超对合或分次对合的超代数的钩子定理

Hook Theorem for Superalgebras with Superinvolution or Graded Involution

本文在特征零域上具有超对合或分次对合的PI-超代数中，证明了多重线性#-超恒等式的钩子定理，并由此导出Amitsur恒等式的类似物，以对称群表示刻画恒等式的组合特征。

分次环的$PBW$-变形

$PBW$-deformations of graded rings

本文在一般框架下证明了经典Poincaré-Birkhoff-Witt定理的多个版本，扩展了已有结果，并讨论了相关应用与例子。

BGG correspondence and Roemer's theorem on an exterior algebra

Let E = K< y_1, ..., y_n > be the exterior algebra. The ``(cohomological) distinguished pairs" of a graded E-module M describe the growth of a minimal graded injective resolution of M. Roemer gave a duality theorem between the distinguished pairs of M and those of its dual M^*. In this paper, we show that under Bernstein-Gel'fand-Gel'fand correspondence, his theorem is translated into a natural corollary of local duality for (complexes of) graded S=K[x_1, >..., x_n]-modules. Using this idea, we also give a Z^n-graded version of Roemer's theorem.

Matrix factorizations via Koszul duality

In this paper we prove a version of curved Koszul duality for Z/2Z-graded curved coalgebras and their coBar differential graded algebras. A curved version of the homological perturbation lemma is also obtained as a useful technical tool for studying curved (co)algebras and precomplexes. The results of Koszul duality can be applied to study the category of matrix factorizations MF(R,W). We show how Dyckerhoff's generating results fit into the framework of curved Koszul duality theory. This enables us to clarify the relationship between the Borel-Moore Hochschild homology of curved (co)algebras …

群胚分次环的Hopkins-Levitzki型定理

Hopkins-Levitzki Type Theorems for Groupoid Graded Rings

该研究针对群胚分次环，引入分次理想的左/右逐对象幂零性概念，推广Hopkins-Levitzki定理，证明三类Γ₀-Artinian环为Γ₀-Noetherian环，并用反例说明相关结论。

Monadicity theorem and weighted projective lines of tubular type

We formulate a version of Beck's monadicity theorem for abelian categories, which is applied to the equivariantization of abelian categories with respect to a finite group action. We prove that the equivariantization is compatible with the construction of quotient abelian categories by Serre subcategories. We prove that the equivariantization of the graded module category over a graded ring is equivalent to the graded module category over the same ring but with a different grading. We deduce from these results two equivalences between the category of (equivariant) coherent sheaves on a weighte…