Difference operators and difference equations on lattices, or grids, up to the elliptic hypergeometric case

Fuente: arXiv
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Main Author: Magnus, Alphonse P.
Format: Preprint
Published: 2025
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author Magnus, Alphonse P.
author_facet Magnus, Alphonse P.
contents It is shown how to define difference operators and equations on particular lattices $\{x_n\}$, $2n\in\mathbb{Z}$, such that the divided difference operator $(\mathcal{D}f)(x_{n+1/2})= (f(x_{n+1})-f(x_n))/(x_{n+1}-x_n)$ has the property that $\mathcal{D}f$ is a rational function of degree $2d$ when $f$ is a rational function of degree $d$. It is then shown that the $x_n$s are in the most general case values of an elliptic function at a sequence of arguments in arithmetic progression (\emph{elliptic lattice}). Many special and limit cases, down to the most elementary ones, are considered too. First and second order difference operators and equations are constructed, up to the simplest elliptic hypergeometric ones. One also shows orthogonality and biorthogonality properties of rational solutions to some of these difference equations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21871
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Difference operators and difference equations on lattices, or grids, up to the elliptic hypergeometric case
Magnus, Alphonse P.
Number Theory
33C05, 33D15, 33E05, 39A13, 39A70, 41A05
It is shown how to define difference operators and equations on particular lattices $\{x_n\}$, $2n\in\mathbb{Z}$, such that the divided difference operator $(\mathcal{D}f)(x_{n+1/2})= (f(x_{n+1})-f(x_n))/(x_{n+1}-x_n)$ has the property that $\mathcal{D}f$ is a rational function of degree $2d$ when $f$ is a rational function of degree $d$. It is then shown that the $x_n$s are in the most general case values of an elliptic function at a sequence of arguments in arithmetic progression (\emph{elliptic lattice}). Many special and limit cases, down to the most elementary ones, are considered too. First and second order difference operators and equations are constructed, up to the simplest elliptic hypergeometric ones. One also shows orthogonality and biorthogonality properties of rational solutions to some of these difference equations.
title Difference operators and difference equations on lattices, or grids, up to the elliptic hypergeometric case
topic Number Theory
33C05, 33D15, 33E05, 39A13, 39A70, 41A05
url https://arxiv.org/abs/2510.21871