On incomparability and related cardinal functions on ultraproducts of Boolean algebras
Logic
2007-05-23 v1 General Topology
Abstract
Let C denote any of the following cardinal characteristics of Boolean algebras: incomparability, spread, character, pi-character, hereditary Lindelof number, hereditary density. It is shown to be consistent that there exists a sequence <B_i:i<kappa> of Boolean algebras and an ultrafilter D on kappa such that C(prod_{i<kappa}B_i/D)<|prod_{i<kappa}C(B_i)/D|. This answers a number of problems posed by Monk.
Keywords
Cite
@article{arxiv.math/9903116,
title = {On incomparability and related cardinal functions on ultraproducts of Boolean algebras},
author = {Saharon Shelah and Otmar Spinas},
journal= {arXiv preprint arXiv:math/9903116},
year = {2007}
}