On Equal Consecutive Values of Multiplicative Functions
Discrete analysis (2024)
Voir la notice de l'article provenant de la source Scholastica
arXiv
Let $f: \mathbb{N} \to \mathbb{C}$ be a multiplicative function for which $$ \sum_{p : \, |f(p)| \neq 1} \frac{1}{p} = \infty. $$ We show under this condition alone that for any integer $h \neq 0$ the set $$ \{n \in \mathbb{N} : f(n) = f(n+h) \neq 0\} $$ has logarithmic density 0. We also prove a converse result, along with an application to the Fourier coefficients of holomorphic cusp forms.
The proof involves analysing the value distribution of $f$ using the compositions $|f|^{it}$, relying crucially on various applications of Tao's theorem on logarithmically-averaged correlations of non-pretentious multiplicative functions. Further key inputs arise from the inverse theory of sumsets in continuous additive combinatorics.
Alexander P. Mangerel. On Equal Consecutive Values of Multiplicative Functions. Discrete analysis (2024). http://geodesic.mathdoc.fr/item/DAS_2024_a9/
@article{DAS_2024_a9,
author = {Alexander P. Mangerel},
title = {On {Equal} {Consecutive} {Values} of {Multiplicative} {Functions}},
journal = {Discrete analysis},
year = {2024},
language = {en},
url = {http://geodesic.mathdoc.fr/item/DAS_2024_a9/}
}