Tag Archives: P-Ideal Dichotomy

Knaster and friends III: Subadditive colorings

Joint work with Chris Lambie-Hanson. Abstract. We continue our study of strongly unbounded colorings, this time focusing on subadditive maps. In Part I of this series, we showed that, for many pairs of infinite cardinals θ<κ, the existence … Continue reading

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The S-space problem, and the cardinal invariant p

Recall that an S-space is a regular hereditarily separable topological space which is not hereditarily Lindelöf. Do they exist? Consistently, yes. However, Szentmiklóssy proved that compact S-spaces do not exist, assuming Martin’s Axiom. Pushing this further, Todorcevic later proved that … Continue reading

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The P-Ideal Dichotomy and the Souslin Hypothesis

John Krueger is visiting Toronto these days, and in a conversation today, we asked ourselves how do one prove the Abraham-Todorcevic theorem that PID implies SH. Namely, that the next statement implies that there are no Souslin trees: Definition. The … Continue reading

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Dushnik-Miller for regular cardinals (part 3)

Here is what we already know about the Dushnik-Miller theorem in the case of ω1 (given our earlier posts on the subject): ω1(ω1,ω+1)2 holds in ZFC; ω1(ω1,ω+2)2 may consistently fail; ω1(ω1,ω1)2 fails in ZFC. In this post, we shall provide … Continue reading

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