English

Twisted patterns in large subsets of $\mathbb{Z}^N$

Dynamical Systems 2015-12-08 v1 Combinatorics Number Theory

Abstract

Let EZNE \subset \mathbb{Z}^N be a set of positive upper Banach density and let Γ<GLN(Z)\Gamma < \operatorname{GL}_N(\mathbb{Z}) be a finitely generated, strongly irreducible subgroup whose Zariski closure in GLN(R)\operatorname{GL}_N(\mathbb{R}) is a Zariski connected semisimple group with no compact factors. Let YY be any set and suppose that Ψ:ZNY\Psi : \mathbb{Z}^N \rightarrow Y is a Γ\Gamma-invariant function. We prove that for every positive integer mm, there exists a positive integer kk with the property that for every finite set FZNF \subset \mathbb{Z}^N with F=m|F| = m, we have Ψ(kF)Ψ(Eb)for some bE. \Psi(kF) \subset \Psi(E-b) \quad \textrm{for some $b \in E$}. Furthermore, if EE is an aperiodic Bohro_o-set, we can choose k=1k = 1 and b=0b = 0. As one of many applications of this result, we show that if EoZE_o \subset \mathbb{Z} has positive upper Banach density, then, for any integer mm, there exists an integer kk with the property for \emph{every} finite set FZF \subset \mathbb{Z}, we can find x,y,zEox,y,z \in E_o such that k2F{(ux)2+(vy)2(wz)2:u,v,wEo}. k^2 F \subset \big\{ (u-x)^2 + (v-y)^2 - (w-z)^2 \, : \, u,v,w \in E_o \big\}. In particular, if EoZE_o \subset \mathbb{Z} is an aperiodic Bohro_o-set, then every integer can be written on the form u2+v2w2u^2 + v^2 - w^2 for some u,v,wEou,v,w \in E_o. Our techniques use recent results by Benoist-Quint and Bourgain-Furman-Lindenstrauss-Mozes on equidistribution of random walks on automorphism groups of tori.

Keywords

Cite

@article{arxiv.1512.01719,
  title  = {Twisted patterns in large subsets of $\mathbb{Z}^N$},
  author = {Michael Björklund and Kamil Bulinski},
  journal= {arXiv preprint arXiv:1512.01719},
  year   = {2015}
}

Comments

17 pages, no figures

R2 v1 2026-06-22T12:02:22.759Z