English

Sendov's conjecture for sufficiently high degree polynomials

Complex Variables 2022-06-02 v2

Abstract

Sendov's conjecture asserts that if a complex polynomial ff of degree n2n \geq 2 has all of its zeroes in closed unit disk {z:z1}\{ z: |z| \leq 1 \}, then for each such zero λ0\lambda_0 there is a zero of the derivative ff' in the closed unit disk {z:zλ01}\{ z: |z-\lambda_0| \leq 1 \}. This conjecture is known for n<9n < 9, but only partial results are available for higher nn. We show that there exists a constant n0n_0 such that Sendov's conjecture holds for nn0n \geq n_0. For λ0\lambda_0 away from the origin and the unit circle we can appeal to the prior work of D\'egot and Chalebgwa; for λ0\lambda_0 near the unit circle we refine a previous argument of Miller (and also invoke results of Chijiwa when λ0\lambda_0 is extremely close to the unit circle); and for λ0\lambda_0 near the origin we introduce a new argument using compactness methods, balayage, and the argument principle.

Keywords

Cite

@article{arxiv.2012.04125,
  title  = {Sendov's conjecture for sufficiently high degree polynomials},
  author = {Terence Tao},
  journal= {arXiv preprint arXiv:2012.04125},
  year   = {2022}
}

Comments

38 pages, 5 figures. To appear, Acta Mathematica. Referee comments incorporated

R2 v1 2026-06-23T20:48:05.054Z