English

Charting the $q$-Askey scheme. III. Verde-Star scheme for $q=1$

Classical Analysis and ODEs 2025-01-09 v2

Abstract

Following Verde-Star, Linear Algebra Appl. 627 (2021), we label families of orthogonal polynomials in the q=1q=1 Askey scheme together with their hypergeometric representations by three sequences xk,hk,gkx_k, h_k, g_k of polynomials in kk, two of degree 2 and one of degree 4, satisfying certain constraints. Except for the Hermite polynomials, this gives rise to a precise classification and a very simple uniform parametrization of these families together with their limit transitions. This is displayed in a graphical scheme. We also discuss limits from the qq-case to the case q=1q=1, although this cannot be done in a uniform way.

Keywords

Cite

@article{arxiv.2307.06668,
  title  = {Charting the $q$-Askey scheme. III. Verde-Star scheme for $q=1$},
  author = {Tom H. Koornwinder},
  journal= {arXiv preprint arXiv:2307.06668},
  year   = {2025}
}

Comments

v2: minor corrections, 16 pages, 2 figures; to appear in "Orthogonal polynomials and special functions", K. Castillo and A.J. Dur\'an (eds.), Springer-Verlag (volume dedicated to the memory of Jos\'e Carlos Petronilho)