Sets of Ramsey-limit points and IP-limit points
General Topology
2026-01-21 v1 Dynamical Systems
Logic
Abstract
Let be an uncountable Polish space and let be the Hindman ideal, that is, the family of all which are not -sets. For each sequence taking values in , let be the set of -limit points of . Also, let be the set of -limit points of , that is, the set of ordinary limits of subsequences with . After proving that these two notions do not coincide in general, we show that both families of nonempty sets of the type and of the type are precisely the class of nonempty analytic subsets of . An analogous result holds also for Ramsey convergence. In the proofs, we use the concept of partition regular functions introduced in J. Symb. Log. (2024) [doi:10.1017/jsl.2024.8], which provide a unified approach to these types of convergence.
Keywords
Cite
@article{arxiv.2601.12187,
title = {Sets of Ramsey-limit points and IP-limit points},
author = {Rafał Filipów and Adam Kwela and Paolo Leonetti},
journal= {arXiv preprint arXiv:2601.12187},
year = {2026}
}