On some classification problems of multiplicative functions

Fuente: arXiv
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Main Authors: Kasjan, S., Klurman, O., Lemańczyk, M.
Format: Preprint
Published: 2025
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author Kasjan, S.
Klurman, O.
Lemańczyk, M.
author_facet Kasjan, S.
Klurman, O.
Lemańczyk, M.
contents We prove that a multiplicative function $f:\mathbb{N}\to\mathbb{C}$ is Toeplitz if and only if there are a Dirichlet character $χ$ and a finite subset $F$ of prime numbers such that $f(n)=χ(n)$ for each $n$ which is coprime to all numbers from $F$. All such functions bounded by~1 are necessarily pretentious and they have exactly one Furstenberg system. Moreover, we characterize the class of pretentious functions that have precisely one Furstenberg system as those being Besicovitch (rationally) almost periodic. As a consequence, we show that the corrected Elliott's conjecture implies Frantzikinakis-Host's conjecture on the uniqueness of Furstenberg system for all real-valued bounded by~1 multiplicative functions. We also clarify relations between different classes of aperiodic multiplicative functions.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07277
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On some classification problems of multiplicative functions
Kasjan, S.
Klurman, O.
Lemańczyk, M.
Number Theory
Dynamical Systems
37A44, 11N37
We prove that a multiplicative function $f:\mathbb{N}\to\mathbb{C}$ is Toeplitz if and only if there are a Dirichlet character $χ$ and a finite subset $F$ of prime numbers such that $f(n)=χ(n)$ for each $n$ which is coprime to all numbers from $F$. All such functions bounded by~1 are necessarily pretentious and they have exactly one Furstenberg system. Moreover, we characterize the class of pretentious functions that have precisely one Furstenberg system as those being Besicovitch (rationally) almost periodic. As a consequence, we show that the corrected Elliott's conjecture implies Frantzikinakis-Host's conjecture on the uniqueness of Furstenberg system for all real-valued bounded by~1 multiplicative functions. We also clarify relations between different classes of aperiodic multiplicative functions.
title On some classification problems of multiplicative functions
topic Number Theory
Dynamical Systems
37A44, 11N37
url https://arxiv.org/abs/2505.07277