Algorithms for computing norms and characteristic polynomials on general Drinfeld modules

Fuente: arXiv
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Main Authors: Caruso, Xavier, Leudière, Antoine
Format: Preprint
Published: 2023
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author Caruso, Xavier
Leudière, Antoine
author_facet Caruso, Xavier
Leudière, Antoine
contents We provide two families of algorithms to compute characteristic polynomials of endomorphisms and norms of isogenies of Drinfeld modules. Our algorithms work for Drinfeld modules of any rank, defined over any base curve. When the base curve is $\mathbb P^1_{\mathbb F_q}$, we do a thorough study of the complexity, demonstrating that our algorithms are, in many cases, the most asymptotically performant. The first family of algorithms relies on the correspondence between Drinfeld modules and Anderson motives, reducing the computation to linear algebra over a polynomial ring. The second family, available only for the Frobenius endomorphism, is based on a formula expressing the characteristic polynomial of the Frobenius as a reduced norm in a central simple algebra.
format Preprint
id arxiv_https___arxiv_org_abs_2307_02879
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Algorithms for computing norms and characteristic polynomials on general Drinfeld modules
Caruso, Xavier
Leudière, Antoine
Symbolic Computation
Number Theory
We provide two families of algorithms to compute characteristic polynomials of endomorphisms and norms of isogenies of Drinfeld modules. Our algorithms work for Drinfeld modules of any rank, defined over any base curve. When the base curve is $\mathbb P^1_{\mathbb F_q}$, we do a thorough study of the complexity, demonstrating that our algorithms are, in many cases, the most asymptotically performant. The first family of algorithms relies on the correspondence between Drinfeld modules and Anderson motives, reducing the computation to linear algebra over a polynomial ring. The second family, available only for the Frobenius endomorphism, is based on a formula expressing the characteristic polynomial of the Frobenius as a reduced norm in a central simple algebra.
title Algorithms for computing norms and characteristic polynomials on general Drinfeld modules
topic Symbolic Computation
Number Theory
url https://arxiv.org/abs/2307.02879