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Bibliographic Details
Main Authors: Anderson, Theresa C., Bertelli, Adam, O'Dorney, Evan M.
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2406.18970
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author Anderson, Theresa C.
Bertelli, Adam
O'Dorney, Evan M.
author_facet Anderson, Theresa C.
Bertelli, Adam
O'Dorney, Evan M.
contents We study the Galois groups $G_f$ of degree $2n$ reciprocal (a.k.a. palindromic) polynomials $f$ of height at most $H$, finding that $G_f$ falls short of the maximal possible group $S_2 \wr S_n$ for a proportion of all $f$ bounded above and below by constant multiples of $H^{-1} \log H$, whether or not $f$ is required to be monic. This answers a 1998 question of Davis-Duke-Sun and extends Bhargava's 2023 resolution of van der Waerden's 1936 conjecture on the corresponding question for general polynomials. Unlike in that setting, the dominant contribution comes not from reducible polynomials but from those $f$ for which $(-1)^n f(1) f(-1)$ is a square, causing $G_f$ to lie in an index-$2$ subgroup.
format Preprint
id arxiv_https___arxiv_org_abs_2406_18970
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Galois groups of reciprocal polynomials and the van der Waerden-Bhargava theorem
Anderson, Theresa C.
Bertelli, Adam
O'Dorney, Evan M.
Number Theory
11R32, 11R45, 11C08, 11N35, 20E22
We study the Galois groups $G_f$ of degree $2n$ reciprocal (a.k.a. palindromic) polynomials $f$ of height at most $H$, finding that $G_f$ falls short of the maximal possible group $S_2 \wr S_n$ for a proportion of all $f$ bounded above and below by constant multiples of $H^{-1} \log H$, whether or not $f$ is required to be monic. This answers a 1998 question of Davis-Duke-Sun and extends Bhargava's 2023 resolution of van der Waerden's 1936 conjecture on the corresponding question for general polynomials. Unlike in that setting, the dominant contribution comes not from reducible polynomials but from those $f$ for which $(-1)^n f(1) f(-1)$ is a square, causing $G_f$ to lie in an index-$2$ subgroup.
title Galois groups of reciprocal polynomials and the van der Waerden-Bhargava theorem
topic Number Theory
11R32, 11R45, 11C08, 11N35, 20E22
url https://arxiv.org/abs/2406.18970