The number of rational iterated preimages of the origin under unicritical polynomial maps

Fuente: arXiv
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Main Author: Sano, Kaoru
Format: Preprint
Published: 2025
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_version_ 1866912651931549696
author Sano, Kaoru
author_facet Sano, Kaoru
contents We study rational iterated preimages of the origin under unicritical maps $f_{d,c}(x)=x^d+c$. Earlier works of Faber--Hutz--Stoll and Hutz--Hyde--Krause established finiteness and conditional bounds in the quadratic case. Building on this, we prove that for $d=2$ and $c \in \mathbb Q\setminus\{0,-1\}$ there are no rational fourth preimages of the origin, and for all $d \geq 3$ there are no rational second preimages outside trivial cases. The proof relies on geometric analysis of preimage curves, the elliptic Chabauty method, and Diophantine reduction. As a result, we determine the number of rational iterated preimages of $0$ under $f_{d,c}$ for all $d\geq 2$.
format Preprint
id arxiv_https___arxiv_org_abs_2510_14397
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The number of rational iterated preimages of the origin under unicritical polynomial maps
Sano, Kaoru
Number Theory
Algebraic Geometry
Dynamical Systems
14G05, 14Q05, 37P55
We study rational iterated preimages of the origin under unicritical maps $f_{d,c}(x)=x^d+c$. Earlier works of Faber--Hutz--Stoll and Hutz--Hyde--Krause established finiteness and conditional bounds in the quadratic case. Building on this, we prove that for $d=2$ and $c \in \mathbb Q\setminus\{0,-1\}$ there are no rational fourth preimages of the origin, and for all $d \geq 3$ there are no rational second preimages outside trivial cases. The proof relies on geometric analysis of preimage curves, the elliptic Chabauty method, and Diophantine reduction. As a result, we determine the number of rational iterated preimages of $0$ under $f_{d,c}$ for all $d\geq 2$.
title The number of rational iterated preimages of the origin under unicritical polynomial maps
topic Number Theory
Algebraic Geometry
Dynamical Systems
14G05, 14Q05, 37P55
url https://arxiv.org/abs/2510.14397