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Strongs-Sequences and Variations on Martin's Axiom

Published online by Cambridge University Press:  20 November 2018

Juris Steprāns*
Affiliation:
York University, Downsview, Ontario
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As part of their study of βωω and βω1ω1, A. Szymanski and H. X. Zhou [3] were able to exploit the following difference between ω, and ω: ω1, contains uncountably many disjoint sets whereas any uncountable family of subsets of ω is, at best, almost disjoint. To translate this distinction between ω1, and ω to a possible distinction between βω1ω1, and βωω they used the fact that if a pairwise disjoint family of sets and a subset of each member of is chosen then it is trivial to find a single set whose intersection with each member is the chosen set. However, they noticed, it is not clear that the same is true if is only a pairwise almost disjoint family even if we only require equality except on a finite set. But any homeomorphism from βω1ω1 to βωω would have to carry a disjoint family of subsets of ω1, to an almost disjoint family of subsets of ω with this property. This observation should motivate the following definition.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1985

References

1. Bell, M., Two Boolean algebras with extreme cellular and compactness properties, to appear in Can. J. Math.CrossRefGoogle Scholar
2. Herink, C., Some applications of iterated forcing, Ph.D. dissertation, University of Wisconsin, Madison.Google Scholar
3. Szymanski, A. and Zhou, H. X., preprint.Google Scholar
4. Tall, F., Some applications of a generalized Martin's Axiom, to appear in Trans. A.M.S.Google Scholar
5. Weiss, W., Versions of Martin's Axiom, to appear in The Handbook of Set Theoretic Topology.Google Scholar