Integer-valued o-minimal functions

Fuente: arXiv
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Main Authors: Bhardwaj, Neer, McCulloch, Raymond, Ramachandran, Nandagopal, Woo, Katharine
Format: Preprint
Published: 2024
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author Bhardwaj, Neer
McCulloch, Raymond
Ramachandran, Nandagopal
Woo, Katharine
author_facet Bhardwaj, Neer
McCulloch, Raymond
Ramachandran, Nandagopal
Woo, Katharine
contents We study $\mathbb{R}_{\textrm{an},\exp}$-definable functions $f:\mathbb{R}\to \mathbb{R}$ that take integer values at all sufficiently large positive integers. If $|f(x)|= O\big(2^{(1+10^{-5})x}\big)$, then we find polynomials $P_1, P_2$ such that $f(x)=P_1(x)+P_2(x)2^x$ for all sufficiently large $x$. Our result parallels classical theorems of Pólya and Selberg for entire functions and generalizes Wilkie's classification for the case of $|f(x)|= O(C^x)$, for some $C<2$. Let $k\in \mathbb{N}$ and $γ_k=\sum_{j=1}^{k} 1/j$. Extending Wilkie's theorem in a separate direction, we show that if $f$ is $k$-$\textit{concordant}$ and $|f(x)|= O(C^{x})$, for some $C<e^{γ_k}+1$, then $f$ must eventually be given by a polynomial. This is an analog of a result by Pila for entire functions.
format Preprint
id arxiv_https___arxiv_org_abs_2404_10737
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Integer-valued o-minimal functions
Bhardwaj, Neer
McCulloch, Raymond
Ramachandran, Nandagopal
Woo, Katharine
Logic
Number Theory
Primary 11U09, 03C64, Secondary 30D20, 26E05
We study $\mathbb{R}_{\textrm{an},\exp}$-definable functions $f:\mathbb{R}\to \mathbb{R}$ that take integer values at all sufficiently large positive integers. If $|f(x)|= O\big(2^{(1+10^{-5})x}\big)$, then we find polynomials $P_1, P_2$ such that $f(x)=P_1(x)+P_2(x)2^x$ for all sufficiently large $x$. Our result parallels classical theorems of Pólya and Selberg for entire functions and generalizes Wilkie's classification for the case of $|f(x)|= O(C^x)$, for some $C<2$. Let $k\in \mathbb{N}$ and $γ_k=\sum_{j=1}^{k} 1/j$. Extending Wilkie's theorem in a separate direction, we show that if $f$ is $k$-$\textit{concordant}$ and $|f(x)|= O(C^{x})$, for some $C<e^{γ_k}+1$, then $f$ must eventually be given by a polynomial. This is an analog of a result by Pila for entire functions.
title Integer-valued o-minimal functions
topic Logic
Number Theory
Primary 11U09, 03C64, Secondary 30D20, 26E05
url https://arxiv.org/abs/2404.10737