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On a Sumset Conjecture of Erdős

Published online by Cambridge University Press:  20 November 2018

Mauro Di Nasso
Affiliation:
Dipartimento di Matematica, Universita' di Pisa, Largo Bruno Pontecorvo 5, Pisa 56127, Italy e-mail: [email protected]
Isaac Goldbring
Affiliation:
Department of Mathematics, Statistics, and Computer Science, University of Illinois at Chicago, Chicago, IL 60607-7045, USA e-mail: [email protected]
Renling Jin
Affiliation:
Department of Mathematics, College of Charleston, Charleston, SC 29424, USA e-mail: [email protected]
Steven Leth
Affiliation:
School of Mathematical Sciences, University of Northern Colorado, Greeley, CO 80639, USA e-mail: [email protected]
Martino Lupini
Affiliation:
Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3 e-mail: [email protected]
Karl Mahlburg
Affiliation:
Department of Mathematics, Louisiana State University, Baton Rouge, LA 70803, USA e-mail: [email protected]
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Abstract

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Erdős conjectured that for any set $A\,\subseteq \,\mathbb{N}$ with positive lower asymptotic density, there are infinite sets $B,\,C\,\subseteq \,\mathbb{N}$ such that $B\,+\,C\,\subseteq \,A$. We verify Erdős’ conjecture in the case where $A$ has Banach density exceeding $\frac{1}{2}$. As a consequence, we prove that, for $A\,\subseteq \,\mathbb{N}$ with positive Banach density (a much weaker assumption than positive lower density), we can find infinite $B,\,C\,\subseteq \,\mathbb{N}$ such that $B\,+\,C$ is contained in the union of $A$ and a translate of $A$. Both of the aforementioned results are generalized to arbitrary countable amenable groups. We also provide a positive solution to Erdős’ conjecture for subsets of the natural numbers that are pseudorandom.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2015

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