English

Combinatorially rich sets in partial semigroups

Combinatorics 2025-02-07 v2

Abstract

There are several notions of size for semigroups that have natural analogues for partial semigroups. Among these are thick, syndetic, central, piecewise syndetic, IP, J, and the more recently introduced notion of combinatorially rich, abbreviated CR. We investigate the notion of CR set for adequate partial semigroups, its relation to other notions, especially J sets, and some surprising differences among them.

Keywords

Cite

@article{arxiv.2307.01096,
  title  = {Combinatorially rich sets in partial semigroups},
  author = {Arpita Ghosh and Neil Hindman},
  journal= {arXiv preprint arXiv:2307.01096},
  year   = {2025}
}

Comments

17 pages, comments are welcome

R2 v1 2026-06-28T11:20:53.132Z