English

Combined exponential patterns in multiplicative $IP^{\star}$ sets

Combinatorics 2023-10-31 v1

Abstract

IPIP sets play fundamental role in arithmetic Ramsey theory. A set is called an additive IPIP set if it is of the form FS(xnnN)={tHxt:HFS\left(\langle x_{n}\rangle_{n\in \mathbb{N}}\right)=\left\{ \sum_{t\in H}x_{t}:H\right. is a nonempty finite subset of N}\left.\mathbb{N}\right\}, whereas it is called a multiplicative IPIP set if it is of the form FP(xnnN)={tHxt:HFP\left(\langle x_{n}\rangle_{n\in \mathbb{N}}\right)=\left\{ \prod_{t\in H}x_{t}:H\right. is a nonempty finite subset of N}\left. \mathbb{N}\right\} for some injective sequence xnnN.\langle x_{n}\rangle_{n\in \mathbb{N}}. An additive IPIP^{\star} (resp. multiplicative IPIP^{\star}) set is a set which intersects every additive IPIP set (resp. multiplicative IPIP set). In \cite{key-1}, V. Bergelson and N. Hindman studied how rich additive IPIP^{\star} sets are. They proved additive IPIP^{\star} sets (AIPAIP^{\star} in short) contain finite sums and finite products of a single sequence. An analogous study was made by A. Sisto in\cite{key-3}, where he proved that multiplicative IPIP^{\star} sets (MIPMIP^{\star} in short) contain exponential tower\footnote{will be defined later} and finite product of a single sequence. However exponential patterns can be defined in two different ways. In this article we will prove that MIPMIP^{\star} sets contain two different exponential patterns and finite product of a single sequence. This immediately improves the result of A. Sisto. We also construct a MIPMIP^\star set, not arising from the recurrence of measurable dynamical systems. Throughout our work we will use the machinery of the algebra of the Stone-\v{C}ech Compactification of N\mathbb{N}.

Cite

@article{arxiv.2310.18873,
  title  = {Combined exponential patterns in multiplicative $IP^{\star}$ sets},
  author = {Pintu Debnath and Sayan Goswami},
  journal= {arXiv preprint arXiv:2310.18873},
  year   = {2023}
}
R2 v1 2026-06-28T13:04:53.196Z