Automorphisms of Plane Curves defined from Chebychev polynomials

Fuente: arXiv
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Autori principali: Tafazolian, Saeed, Top, Jaap
Natura: Preprint
Pubblicazione: 2025
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author Tafazolian, Saeed
Top, Jaap
author_facet Tafazolian, Saeed
Top, Jaap
contents We investigate the automorphism groups of the algebraic curves \[ \mathcal{C}_d : y^d = φ_d(x), \] where $φ_d(x)$ denotes the Chebyshev polynomial of degree $d$, defined over a field $k$ with $p:=\operatorname{char}(k) \nmid 2d$. We determine the full automorphism group of $\mathcal{C}_d$ in all the cases considered in this paper, namely for $d=4$, and more generally when $2d = p^r+1$ or $4d = p^r+1$. For all other $d>4$, Expectation~\ref{3.19} predicts what the automorphism group should be. As an application, we show that certain maximal curves of the same genus are not isomorphic.
format Preprint
id arxiv_https___arxiv_org_abs_2505_01216
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Automorphisms of Plane Curves defined from Chebychev polynomials
Tafazolian, Saeed
Top, Jaap
Algebraic Geometry
We investigate the automorphism groups of the algebraic curves \[ \mathcal{C}_d : y^d = φ_d(x), \] where $φ_d(x)$ denotes the Chebyshev polynomial of degree $d$, defined over a field $k$ with $p:=\operatorname{char}(k) \nmid 2d$. We determine the full automorphism group of $\mathcal{C}_d$ in all the cases considered in this paper, namely for $d=4$, and more generally when $2d = p^r+1$ or $4d = p^r+1$. For all other $d>4$, Expectation~\ref{3.19} predicts what the automorphism group should be. As an application, we show that certain maximal curves of the same genus are not isomorphic.
title Automorphisms of Plane Curves defined from Chebychev polynomials
topic Algebraic Geometry
url https://arxiv.org/abs/2505.01216