English

Conjugates of Pisot numbers

Number Theory 2021-07-23 v1

Abstract

In this paper we investigate the Galois conjugates of a Pisot number q(m,m+1)q \in (m, m+1), m1m \geq 1. In particular, we conjecture that for q(1,2)q \in (1,2) we have q512|q'| \geq \frac{\sqrt{5}-1}{2} for all conjugates qq' of qq. Further, for m3m \geq 3, we conjecture that for all Pisot numbers q(m,m+1)q \in (m, m+1) we have qm+1m2+2m32|q'| \geq \frac{m+1-\sqrt{m^2+2m-3}}{2}. A similar conjecture if made for m=2m =2. We conjecture that all of these bounds are tight. We provide partial supporting evidence for this conjecture. This evidence is both of a theoretical and computational nature. Lastly, we connect this conjecture to a result on the dimension of Bernoulli convolutions parameterized by β\beta, whose conjugate is the reciprocal of a Pisot number.

Cite

@article{arxiv.2010.01511,
  title  = {Conjugates of Pisot numbers},
  author = {Kevin G. Hare and Nikita Sidorov},
  journal= {arXiv preprint arXiv:2010.01511},
  year   = {2021}
}

Comments

17 pages, 2 figures

R2 v1 2026-06-23T19:00:36.969Z