AI中文摘要
设$A=A(\alpha, \beta)$是带权重$(\deg x, \deg y)=(n,m)$且$\beta\neq 0$的graded down-up代数,$\nabla A$是其Beilinson代数。根据Kirkman--Musson--Passman,这样的代数$A$是3维立方AS-正则代数。假设$\gcd(n, m)=1$且$m \geq n$,我们推广了关于$\nabla A$的Hochschild上同调的先前结果。已知情形包括$(n,m) = (1,1)$(Belmans)和$(n = 1,\,m \geq 2)$(Itaba--Ueyama)。本文中,我们通过显式构造投射分解并计算由此产生的表示矩阵的秩,确定了剩余情形$n\geq 2$且$m\geq 2$中$\nabla A$的Hochschild上同调群的维数。作为副产品,对于$m>n>1$,我们证明了与$A$相关的非交换射影方案的导出范畴不等价于任何光滑射影曲面的导出范畴。此外,对于所有$m \geq n \geq 1$,我们描述了关于Yoneda积的Hochschild上同调群$\nabla A$的环结构。
英文摘要
Let $A=A(α, β)$ be a graded down-up algebra with weights $(\mathrm{deg}\, x, \mathrm{deg}\, y)=(n,m)$ and $β\neq 0$, and $\nabla A$ its Beilinson algebra. Such an algebra $A$ is a 3-dimensional cubic AS-regular algebra by Kirkman--Musson--Passman. Assuming $\mathrm{gcd}\,(n, m)=1$ and $m \geq n$, we extend the previous results on the Hochschild cohomology of $\nabla A$. Known cases include $(n,m) = (1,1)$ (Belmans) and $(n = 1,\,m \geq 2)$ (Itaba--Ueyama). In this paper, we determine the dimensions of the Hochschild cohomology groups of $\nabla A$ in the remaining case $n\geq 2$ and $m\geq 2$ by explicitly constructing the projective resolution and computing the ranks of the arising representation matrices. As a byproduct, for $m>n>1$, we show that the derived category of the noncommutative projective scheme associated to $A$ is not equivalent to the derived category of any smooth projective surface. Moreover, for all $m \geq n \geq 1$, we describe the ring structure of the Hochschild cohomology group $\nabla A$ with respect to the Yoneda product.