Differential transcendence of Bell numbers and relatives: a Galois theoretic approach

Fuente: arXiv
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Autori principali: Bostan, Alin, Di Vizio, Lucia, Raschel, Kilian
Natura: Preprint
Pubblicazione: 2020
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author Bostan, Alin
Di Vizio, Lucia
Raschel, Kilian
author_facet Bostan, Alin
Di Vizio, Lucia
Raschel, Kilian
contents In 2003 Klazar proved that the ordinary generating function of the sequence of Bell numbers is differentially transcendental over the field $\mathbb{C}(\{t\})$ of meromorphic functions at $0$. We show that Klazar's result is an instance of a general phenomenon that can be proven in a compact way using difference Galois theory. We present the main principles of this theory in order to prove a general result about differential transcendence over $\mathbb{C}(\{t\})$, that we apply to many other (infinite classes of) examples of generating functions, including as very special cases the ones considered by Klazar. Most of our examples belong to Sheffer's class, well studied notably in umbral calculus. They all bring concrete evidence in support to the Pak-Yeliussizov conjecture, according to which a sequence whose both ordinary and exponential generating functions satisfy nonlinear differential equations with polynomial coefficients necessarily satisfies a linear recurrence with polynomial coefficients.
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id arxiv_https___arxiv_org_abs_2012_15292
institution arXiv
publishDate 2020
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spellingShingle Differential transcendence of Bell numbers and relatives: a Galois theoretic approach
Bostan, Alin
Di Vizio, Lucia
Raschel, Kilian
Number Theory
Classical Analysis and ODEs
Combinatorics
In 2003 Klazar proved that the ordinary generating function of the sequence of Bell numbers is differentially transcendental over the field $\mathbb{C}(\{t\})$ of meromorphic functions at $0$. We show that Klazar's result is an instance of a general phenomenon that can be proven in a compact way using difference Galois theory. We present the main principles of this theory in order to prove a general result about differential transcendence over $\mathbb{C}(\{t\})$, that we apply to many other (infinite classes of) examples of generating functions, including as very special cases the ones considered by Klazar. Most of our examples belong to Sheffer's class, well studied notably in umbral calculus. They all bring concrete evidence in support to the Pak-Yeliussizov conjecture, according to which a sequence whose both ordinary and exponential generating functions satisfy nonlinear differential equations with polynomial coefficients necessarily satisfies a linear recurrence with polynomial coefficients.
title Differential transcendence of Bell numbers and relatives: a Galois theoretic approach
topic Number Theory
Classical Analysis and ODEs
Combinatorics
url https://arxiv.org/abs/2012.15292