Galois Groups of Trinomials with Small Coefficients
Abstract
We calculate the Galois group of f = xn + axk + b ∈ ℤ[ x ] over ℚ for all 1 ≤ | ab | ≤ 3, n sufficiently large and k coprime to n. In particular, we prove that the Galois group of f is the maximal one that its factorization type allows. We give a criterion for the Galois group of a factor of a trinomial to be symmetric, with an eye towards future applications. To the best of our knowledge, the only previously known explicit example of polynomials of degree n with bounded coefficients and Galois group Sn is xn − x − 1, while recent results show that the probability that a random polynomial of degree n with reasonably bounded coefficients has Galois group Sn tends to $1$ as n tends to infinity. Using our calculation, one can construct many new such explicit examples.
Related
- Galois groups of integer polynomials with prescribed coefficients
- Galois groups of Apéry-like series modulo primes
- Infinite free pro-p products as absolute Galois groups
- Galois coinvariants and fundamental groups of arithmetic schemes
- Construction of Galois modules describing ideal class groups and applications to Iwasawa theory
BibTeX
@misc{garmi2026galois,
title = {{Galois Groups of Trinomials with Small Coefficients}},
author = {Hilel Garmi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22764},
eprint = {2610.22764},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22764},
}
RIS
TY - UNPB
TI - Galois Groups of Trinomials with Small Coefficients
AU - Hilel Garmi
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.22764
UR - https://arxiv.org/abs/2610.22764
AB - We calculate the Galois group of f = x^n + ax^k + b ∈ ℤ[ x ] over ℚ for all 1 ≤ | ab | ≤ 3, n sufficiently large and k coprime to n. In particular, we prove that the Galois group of f is the maximal one that its factorization type allows. We give a criterion for the Galois group of a factor of a trinomial to be symmetric, with an eye towards future applications. To the best of our knowledge, the only previously known explicit example of polynomials of degree n with bounded coefficients and Galois group S_n is x^n − x − 1, while recent results show that the probability that a random polynomial of degree n with reasonably bounded coefficients has Galois group S_n tends to $1$ as n tends to infinity. Using our calculation, one can construct many new such explicit examples.
ER -