English

Maximum Principle and Asymptotic Properties of Hermite--Pad\'e Polynomials

Complex Variables 2021-09-24 v2

Abstract

In the paper, we discuss how it would be possible to succeed in Stahl's novel approach, 1987--1988, to explore Hermite--Pad\'e polynomials based on Riemann surface properties. In particular, we explore the limit zero distribution of type I Hermite--Pad\'e polynomials Qn,0,Qn,1,Qn,2Q_{n,0},Q_{n,1},Q_{n,2}, degQn,jn\operatorname{deg}{Q_{n,j}}\leq{n}, for a collection of three analytic elements [1,f,f2][1,f_\infty,f^2_\infty]. The element ff_\infty is an element of a function ff from the class C(z,w)\mathbb C(z,w) where ww is supposed to be from the class Z±1/2([1,1])Z_{\pm1/2}([-1,1]) of multivalued analytic functions generated by the inverse Zhukovskii function with the exponents from the set {±1/2}\{\pm1/2\}. The Riemann surface corresponding to fC(z,w)f\in\mathbb C(z,w) is a four-sheeted Riemann surface R4(w)\mathfrak R_4(w) and all branch points of ff are of the first order (i.e., all branch points are of square root type). Since the algebraic function fC(z,w)f\in\mathbb C(z,w) is of fourth order and we consider the triple of the analytic elements [1,f,f2][1,f_\infty,f^2_\infty] but not the quadruple [1,f,f2,f3][1,f_\infty,f^2_\infty,f^3_\infty] ones, the result is new and does not follow from the known results. As in previous paper arXiv: 2108.00339 and following to Stahl's ideas, 1987--1988, we do not use the orthogonality relations at all. The proof is based on the maximum principle only.

Keywords

Cite

@article{arxiv.2109.10144,
  title  = {Maximum Principle and Asymptotic Properties of Hermite--Pad\'e Polynomials},
  author = {Sergey P. Suetin},
  journal= {arXiv preprint arXiv:2109.10144},
  year   = {2021}
}

Comments

2 figures, 13 pages, Bibliography: 45 titles