dorsal/arxiv
View SchemaThe Galois Structure of the Spaces of polydifferentials on the Drinfeld Curve
| Authors | Denver-James Logan Marchment, Bernhard Köck |
|---|---|
| Categories | |
| ArXiv ID | 2601.09956vv1 |
| URL | https://arxiv.org/abs/2601.09956 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
Let $C$ be a smooth projective curve over an algebraically closed field ${\mathbb{F}}$ equipped with the action of a finite group $G$. When $p =\textrm{char}(\mathbb{F})$ divides the order of $G$, the long-standing problem of computing the induced representation of $G$ on the space $H^0(C,\Omega^{\otimes m}_C)$ of globally holomorphic polydifferentials remains unsolved in general. In this paper, we study the case of the group $G = \mathrm{SL}_2(\mathbb{F}_q)$ (where $q$ is a power of~$p$) acting on the Drinfeld curve $C$ which is the projective plane curve given by the equation $XY^q-X^qY-Z^{q+1} = 0$. When $q = p$, we fully decompose $H^0(C,\Omega^{\otimes m}_C)$ as a direct sum of indecomposable $\mathbb{F}[G]$-modules. For arbitrary $q$, we give a partial decomposition in terms of an explicit $\mathbb{F}$-basis of $H^0(C,\Omega^{\otimes m}_C)$.
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"abstract": "Let $C$ be a smooth projective curve over an algebraically closed field ${\\mathbb{F}}$ equipped with the action of a finite group $G$. When $p =\\textrm{char}(\\mathbb{F})$ divides the order of $G$, the long-standing problem of computing the induced representation of $G$ on the space $H^0(C,\\Omega^{\\otimes m}_C)$ of globally holomorphic polydifferentials remains unsolved in general. In this paper, we study the case of the group $G = \\mathrm{SL}_2(\\mathbb{F}_q)$ (where $q$ is a power of~$p$) acting on the Drinfeld curve $C$ which is the projective plane curve given by the equation $XY^q-X^qY-Z^{q+1} = 0$. When $q = p$, we fully decompose $H^0(C,\\Omega^{\\otimes m}_C)$ as a direct sum of indecomposable $\\mathbb{F}[G]$-modules. For arbitrary $q$, we give a partial decomposition in terms of an explicit $\\mathbb{F}$-basis of $H^0(C,\\Omega^{\\otimes m}_C)$.",
"arxiv_id": "2601.09956",
"authors": [
"Denver-James Logan Marchment",
"Bernhard K\u00f6ck"
],
"categories": [
"math.AG"
],
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "The Galois Structure of the Spaces of polydifferentials on the Drinfeld Curve",
"url": "https://arxiv.org/abs/2601.09956",
"version": "v1"
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