A note on a new ideal
Combinatorics
2017-09-26 v3
Abstract
In this paper we study a new ideal . The main result is the following: an ideal is not weakly Ramsey if and only if it is above in the Kat\v{e}tov order. Weak Ramseyness was introduced by Laflamme in order to characterize winning strategies in a certain game. We apply result of Natkaniec and Szuca to conclude that is critical for ideal convergence of sequences of quasi-continuous functions. We study further combinatorial properties of and weak Ramseyness. Answering a question of Filip\'ow et al. we show that is not -Ramsey, but every ideal on isomorphic to is Mon (every sequence of reals contains a monotone subsequence indexed by a -positive set).
Keywords
Cite
@article{arxiv.1409.8335,
title = {A note on a new ideal},
author = {Adam Kwela},
journal= {arXiv preprint arXiv:1409.8335},
year = {2017}
}