R. -O. Buchweitz, S. Liu
We construct Artin algebras with vanishing first Hochschild Cohomology but a loop in their ordinary quiver. Some authors guessed earlier that such examples could not exist.
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Let $A$ be a Koszul Artin-Schelter regular algebra, $σ$ a graded automorphism of $A$ and $δ$ a degree-one $σ$-derivation of $A$. We introduce an invariant for $δ$ called the $σ$-divergence of $δ$. We describe the Nakayama automorphism of the graded Ore extension $B=A[z;σ,δ]$ explicitly using the $σ$-divergence of $δ$, and construct a twisted superpotential $\hatω$ for $B$ so that it is a derivation quotient algebra defined by $\hatω$. We also determine all graded Ore extensions of noetherian Artin-Schelter regular algebras of dimension 2 and compute their Nakayama automorphisms.
Nakayama automorphisms of graded double Ore extensions of Koszul Artin-Schelter regular algebras with nontrivial skew derivations
本文研究Koszul Artin-Schelter正则代数的分次双重Ore扩张，通过构造极小自由预解证明其保持Koszul性质，并引入$ς$-散度同调不变量精确刻画中山自同构，进而构造扭曲超势实现导子商代数同构。
Rank two Artin-Schelter regular algebras and non commuting derivations
本文研究由满足特定交换关系的导子 $Δ$ 和 $Γ$ 构造的代数 $(A,\ast)$，证明其过滤半经典极限为秩二泊松结构，并在每个至少四维的维度上给出 Artin-Schelter 正则代数和 Calabi-Yau 代数的多参数族新例子。
Let $A$ be a special biserial algebra over an algebraically closed field. We show that the first Hohchshild cohomology group of $A$ with coefficients in the bimodule $A$ vanishes if and only if $A$ is representation finite and simply connected (in the sense of Bongartz and Gabriel), if and only if the Euler characteristic of $Q$ equals the number of indecomposable non uniserial projective injective $A$-modules (up to isomorphism). Moreover, if this is the case, then all the higher Hochschild cohomology groups of $A$ vanish.
In the present paper we prove the existence outer derivations finite-dimensional solvable Lie algebras with nilradical of maximal rank and complementary subspace to nilardical of dimension less than rank of the nilradical.
Inner and Outer Twisted Derivations of Cyclic Group Rings
本文研究循环群环上扭曲导子的内、外性，建立了内导子及一般扭曲导子的充分必要条件，并据此给出所有扭曲导子均为内导子以及存在非平凡外扭曲导子的充分条件。
In this paper we prove that every finite-dimensional nilpotent restricted Lie algebra over a field of prime characteristic has an outer restricted derivation whose square is zero unless the restricted Lie algebra is a torus or it is one-dimensional or it is isomorphic to the three-dimensional Heisenberg algebra in characteristic two as an ordinary Lie algebra. This result is the restricted analogue of a result of Tôgô on the existence of nilpotent outer derivations of ordinary nilpotent Lie algebras in arbitrary characteristic and the Lie-theoretic analogue of a classical group-theoretic resul…
Let $A$ be a Koszul Artin-Schelter regular algebra with Nakayama automorphism $ξ$. We show that the Yoneda Ext-algebra of the skew polynomial algebra $A[z;ξ]$ is a trivial extension of a Frobenius algebra. Then we prove that $A[z;ξ]$ is Calabi-Yau; and hence each Koszul Artin Schelter regular algebra is a subalgebra of a Koszul Calabi-Yau algebra. A superpotential $\hat{w}$ is also constructed so that the Calabi-Yau algebra $A[z;ξ]$ is isomorphic to the derivation quotient of $\hat{w}$. The Calabi-Yau property of a skew polynomial algebra with coefficients in a PBW-deformation of a Koszul Arti…
We show that the Hochschild cohomology of a monomial algebra over a field of characteristic zero vanishes from degree two if the first Hochschild cohomology is semisimple as a Lie algebra. We also prove that first Hochschild cohomology of a radical square zero algebra is reductive as a Lie algebra. In the case of the multiple loops quiver, we obtain the Lie algebra of square matrices of size equal to the number of loops.
Inner and Outer Derivations of $\mathbb{F}V_{8n}$
本文通过给出导子代数的维数与基，显式分类了群代数 $\mathbb{F}V_{8n}$ 的全部导子，并证明非零外导子仅在域特征 $p$ 整除 $n$ 时存在。
Building on work of Gerstenhaber, we show that the space of integrable derivations on an Artin algebra $A$ forms a Lie algebra, and a restricted Lie algebra if $A$ contains a field of characteristic $p$. We deduce that the space of integrable classes in $\HH^1(A)$ forms a (restricted) Lie algebra that is invariant under derived equivalences, and under stable equivalences of Morita type between self-injective algebras. We also provide negative answers to questions about integrable derivations posed by Linckelmann and by Farkas, Geiss and Marcos.
This paper studies the homological determinants and Nakayama automorphisms of not-necessarily-noetherian $m$-Koszul twisted Calabi-Yau or, equivalently, $m$-Koszul Artin-Schelter regular, algebras. Dubois-Violette showed that such an algebra is isomorphic to a derivation quotient algebra D(w,i) for a unique-up-to-scalar-multiples twisted superpotential w in a tensor power of some vector space V. By definition, D(w,i) is the quotient of the tensor algebra TV by the ideal generated by all i-th order left partial derivatives of w. We identify the group of graded algebra automorphisms of D(w,i) wi…
In this paper, we describe the $K$-module $HH^1(L_K(Γ))$ of outer derivations of the Leavitt path algebra $L_K(Γ)$ of a row-finite graph $Γ$ with coefficients in an associative commutative ring $K$ with unit. We give an explicit formula for every outer derivation of $L_K(Γ)$. We also describe the Lie algebra structure of outer derivations of the Toeplitz algebra and we prove that every derivation of the Leavitt path algebra can be extended to a derivation of the corresponding $C^*$-algebra.
We describe derivations and automorphisms of infinite tensor products of matrix algebras. Using this description we show that for a countable--dimensional locally matrix algebra $A$ over a field $\mathbb{F}$ the dimension of the Lie algebra of outer derivations of $A$ and the order of the group of outer automorphisms of $A$ are both equal to $|\mathbb{F}|^{\aleph_0},$ where $|\mathbb{F}|$ is the cardinality of the field $\mathbb{F}.$
Let $\mathbb{F}$ be the underlying base field of characteristic $p>3 $ and denote by $\mathcal{W}$ and $\mathcal{S}$ the even parts of the finite-dimensional generalized Witt Lie superalgebra $W$ and the special Lie superalgebra $S,$ respectively. We first give the generator sets of the Lie algebras $\mathcal{W}$ and $\mathcal{S}.$ Using certain properties of the canonical tori of $\mathcal{W}$ and $\mathcal{S},$ we then determine the derivation algebra of $\mathcal{W}$ and the derivation space of $\mathcal{S} $ to $\mathcal{W},$ where $\mathcal{W}$ is viewed as $\mathcal{S} $-module by means …
The aim of this paper is to describe all inner and all outer derivations of Leavitt path algebra W(n) via explicit formulas. In fact the space of all inner and all outer derivations of the Leavitt path algebra W(n) has been described.
Let $L$ be a finite dimensional Lie algebra over a field $F$. It is well known that the solvable radical $S(L)$ of the algebra $L$ is a characteristic ideal of $L$ if $\char F=0$ and there are counterexamples to this statement in case $\char F=p>0$. We prove that the sum $S(L)$ of all solvable ideals of a Lie algebra $L$ (not necessarily finite dimensional) is a characteristic ideal of $L$ in the following cases: 1) $\char F=0;$ 2) $S(L)$ is solvable and its derived length is less than $\log_{2}p.$ Some estimations (in characteristic 0) for the derived length of ideals $I+D(I)+... +D^{k}(I)$ a…
2-Local derivations on a Block-type Lie algebra
本文研究了块型李代数上的2-局部导数，证明其本质上为导数。
We consider the action of a semisimple Hopf algebra $H$ on an $m$-Koszul Artin-Schelter regular algebra $A$. Such an algebra $A$ is a derivation-quotient algebra for some twisted superpotential $\mathsf{w}$, and we show that the homological determinant of the action of $H$ on $A$ can be easily calculated using $\mathsf{w}$. Using this, we show that the smash product $A\,\#\,H$ is also a derivation-quotient algebra, and use this to explicitly determine a quiver algebra $Λ$ to which $A\,\#\,H$ is Morita equivalent, generalising a result of Bocklandt-Schedler-Wemyss. We also show how $Λ$ can be u…
Outer derivations on blocks of group algebras
研究块群代数的外导出与Hochschild上同调群的关系，证明了多种情况下HH^1(B,B)非零。
It is proved that the derivation algebra of a centerless perfect Lie algebra of arbitrary dimension over any field of arbitrary characteristic is complete and that the holomorph of a centerless perfect Lie algebra is complete if and only if its outer derivation algebra is centerless.
Let $\BB$ be the Lie algebra of Block type with basis $\{L_{\a,i}|\,\a,i\in\Z, i\geq0\}$ and relations $[L_{\a,i},L_{\b,j}]=\left((\a-1)(j+1)-(\b-1)(i+1)\right)L_{\a+\b,i+j}$. In the present paper, the derivation algebra and the automorphism group of $\BB$ are explicitly described. In particular, it is shown that the outer derivation space is 1-dimensional and the inner automorphism group of $\BB$ is trivial.
In this paper we apply a method devised in \cite{HartLarsSilv1D,LarsSilv1D} to the three-dimensional simple Lie algebra $\sll$. One of the main points of this deformation method is that the deformed algebra comes endowed with a canonical twisted Jacobi identity. We show in the present paper that when our deformation scheme is applied to $\sll$ we can, by choosing parameters suitably, deform $\sll$ into the Heisenberg Lie algebra and some other three-dimensional Lie algebras in addition to more exotic types of algebras, this being in stark contrast to the classical deformation schemes where $\s…
In the paper, a method of describing the outer derivations of the group algebra of a finitely presentable group is given. The description of derivations is given in terms of characters of the groupoid of the adjoint action of the group.
In this paper we mainly study the derivations for even part of the finite-dimensional odd Hamiltonian superalgebra $HO$ over a field of prime characteristic. We first give the generator set of $HO_{\bar{0}}.$ Then we determine the homogeneous derivationsfrom $HO_{\bar{0}}$ into $W_{\bar{0}},$ the even part of the generalized Witt superalgebra $W$. Finally, wedetermine the derivation algebra and outer derivation algebra of $HO_{\bar{0}}.$
Counterexamples to the Zassenhaus conjecture on simple modular Lie algebras
本文构造了Zassenhaus关于单模李代数外导代数可解性猜想的无限反例族，证明了特征3下特定维数的单模李代数 $H(2;(1,n))^{(2)}$ 的外导代数不可解，并给出了其外导代数的精确结构。
Almost inner derivations of Lie superalgebras
本文研究李超代数的几乎内导子，证明复数域上有限维单李超代数的几乎内导子均为内导子，并给出与 Sato-Kimura 分类相关的拟约化李超代数上的非内例子。
We describe a grading switching for arbitrary non-associative algebras of prime characteristic p, aimed at producing a new grading of an algebra from a given one. This is inspired by a fundamental tool in the classification theory of modular Lie algebras known as toral switching, which relies on a delicate adaptation of the exponential of a derivation. We trace the development of grading switching, from an early version based on taking the Artin-Hasse exponential of a nilpotent derivation, to a more general version which uses certain generalized Laguerre polynomials playing the role of general…
Local derivations on the Lie algebra $W(2,2)$
本文证明具有外导子的李代数 $W(2,2)$ 上的每个局部导子均为导子，并据此确定形变 $\mathfrak{bms}_3$ 代数上的全部局部导子。
$(σ, τ)$-Derivations of Group Rings with Applications
本文研究群环RG的(σ, τ)-导子，给出映射唯一扩张为(σ, τ)-导子的充要条件，分类内(σ, τ)-导子，并应用于正特征域群代数、二面体群代数及编码理论中IDD码的构造。
Wells exact sequences for $n$-Lie algebras
该研究通过交叉积数据分析n-李代数非阿贝尔扩张的导子与自同构，利用上同调类分类扩张数据，构造相关李代数与群并得到Wells序列，还处理了稀疏交叉积相关内容。
Local Derivations on Conformal Galilei Algebras and Their Central Extensions
本文统一研究了共形伽利略代数在三种中心扩张情形下的局部导子，确定了其结构，并解决了代数自反性问题，揭示了质量中心扩张消除额外局部自由度的关键作用。
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