Mathematics

Commuting variety of r-tuples over the Witt algebra

  • Yufeng YAO ,
  • Yajing ZHANG
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  • Department of Mathematics, Shanghai Maritime University, Shanghai 201306, China

Received date: 2020-01-12

  Online published: 2021-05-26

Abstract

Let ${\mathfrak{g}}$ be the Witt algebra over an algebraically closed field of characteristic $p>3$ , and $r\in\mathbb{Z}_{\geqslant 2}$ . The commuting variety ${{\cal{C}}_{r}}\left( \mathfrak{g} \right)$ of $r$ -tuples over ${\mathfrak{g}}$ is defined as the collection of all $r$ -tuples of pairwise commuting elements in ${\mathfrak{g}}$ . In contrast with Ngo’s work in 2014, for the case of classical Lie algebras, we show that the variety ${{\cal{C}}_{r}}\left( \mathfrak{g} \right)$ is reducible, and there are a total of $\frac{p-1}{2}$ irreducible components. Moreover, the variety $ {{\cal{C}}_{r}}\left( \mathfrak{g} \right) $ is not equidimensional. All irreducible components and their dimensions are precisely determined. In particular, the variety ${{\cal{C}}_{r}}\left( \mathfrak{g} \right)$ is neither normal nor Cohen-Macaulay. These results are different from those for the case of classical Lie algebra, $\mathfrak{sl}_2$ .

Cite this article

Yufeng YAO , Yajing ZHANG . Commuting variety of r-tuples over the Witt algebra[J]. Journal of East China Normal University(Natural Science), 2021 , 2021(3) : 1 -7 . DOI: 10.3969/j.issn.1000-5641.2021.03.001

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