English

Ramsey-like theorems and immunities

Logic 2026-05-12 v2

Abstract

A Ramsey-like theorem is a statement of the form ``For every 2-coloring of [N]2[\mathbb{N}]^2, there exists an infinite set~HNH \subseteq \mathbb{N} such that [H]2[H]^2 avoids some pattern''. We prove that none of these statements are computably trivial, by constructing a computable 2-coloring of [N]2[\mathbb{N}]^2 such that every infinite set avoiding any pattern computes a diagonally non-computable function relative to \emptyset'. We also consider multiple notions of weaknesses based of variants of immunity, and characterize the Ramsey-like theorems which preserve these notions or not, based on the shape of the avoided pattern. This is part of a larger study of the reverse mathematics of Ramsey-like theorems.

Keywords

Cite

@article{arxiv.2508.15597,
  title  = {Ramsey-like theorems and immunities},
  author = {Ahmed Mimouni and Ludovic Patey},
  journal= {arXiv preprint arXiv:2508.15597},
  year   = {2026}
}

Comments

39 pages

R2 v1 2026-07-01T05:00:11.803Z