English

Abundance of arithmetic progressions in $\mathcal{CR}$-sets

Combinatorics 2024-08-22 v4

Abstract

H.Furstenberg and E.Glasner proved that for an arbitrary kNk\in\mathbb{N}, any piecewise syndetic set of integers contains a kk-term arithmetic progression and the collection of such progressions is itself piecewise syndetic in Z.\mathbb{Z}. The above result was extended for arbitrary semigroups by V. Bergelson and N. Hindman, using the algebra of the Stone-\v{C}ech compactification of discrete semigroups. However, they provided an abundance for various types of large sets. In \cite{DHS}, the first author, Neil Hindman and Dona Strauss introduced two notions of large sets, namely, JJ-set and CC-set. In \cite{BG}, V. Bergelson and D. Glasscock introduced another notion of largeness, which is analogous to the notion of JJ-set, namely CR\mathcal{CR}- set. All these sets contain arithmetic progressions of arbitrary length. In \cite{DG}, the second author and S. Goswami proved that for any JJ-set, ANA\subseteq\mathbb{N}, the collection {(a,b):{a,a+b,a+2b,,a+lb}A}\{(a,b):\,\{a,a+b,a+2b,\ldots,a+lb\}\subset A\} is a JJ-set in (N×N,+)(\mathbb{N\times\mathbb{N}},+). In this article, we prove the same for CR\mathcal{CR}-sets.

Keywords

Cite

@article{arxiv.2211.12372,
  title  = {Abundance of arithmetic progressions in $\mathcal{CR}$-sets},
  author = {Dibyendu De and Pintu Debnath},
  journal= {arXiv preprint arXiv:2211.12372},
  year   = {2024}
}

Comments

8 pages. arXiv admin note: substantial text overlap with arXiv:2108.05200

R2 v1 2026-06-28T06:36:00.031Z