The Pythagoras number of fields of transcendence degree $1$ over $\mathbb{Q}$

Fuente: arXiv
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Main Author: Benoist, Olivier
Format: Preprint
Published: 2025
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_version_ 1866913925865406464
author Benoist, Olivier
author_facet Benoist, Olivier
contents We show that any sum of squares in a field of transcendence degree $1$ over $\mathbb{Q}$ is a sum of $5$ squares, answering a question of Pop and Pfister. We deduce this result from a representation theorem, in $k(C)$, for quadratic forms of rank $\geq 5$ with coefficients in $k$, where $C$ is a curve over a number field $k$.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21380
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Pythagoras number of fields of transcendence degree $1$ over $\mathbb{Q}$
Benoist, Olivier
Algebraic Geometry
Number Theory
11E25, 11E12, 14G25, 14G12
We show that any sum of squares in a field of transcendence degree $1$ over $\mathbb{Q}$ is a sum of $5$ squares, answering a question of Pop and Pfister. We deduce this result from a representation theorem, in $k(C)$, for quadratic forms of rank $\geq 5$ with coefficients in $k$, where $C$ is a curve over a number field $k$.
title The Pythagoras number of fields of transcendence degree $1$ over $\mathbb{Q}$
topic Algebraic Geometry
Number Theory
11E25, 11E12, 14G25, 14G12
url https://arxiv.org/abs/2506.21380