Tag Archives: Diamond

Diamond on Kurepa trees

Joint work with Ziemek Kostana and Saharon Shelah. Abstract. We introduce a new weak variation of diamond that is meant to only guess the branches of a Kurepa tree. We demonstrate that this variation is considerably weaker than diamond by … Continue reading

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Diamond on ladder systems and countably metacompact topological spaces

Joint work with Rodrigo Rey Carvalho and Tanmay Inamdar. Abstract. Leiderman and Szeptycki proved that a single Cohen real introduces a ladder system L over 1 for which the space XL is not a Δ-space. They asked whether there is … Continue reading

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Strongest transformations

Joint work with Jing Zhang. Abstract. We continue our study of maps transforming high-dimensional complicated objects into squares of stationary sets. Previously, we proved that many such transformations exist in ZFC, and here we address the consistency of the strongest … Continue reading

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A microscopic approach to Souslin-tree constructions. Part II

Joint work with Ari Meir Brodsky. Abstract. In Part I of this series, we presented the microscopic approach to Souslin-tree constructions, and argued that all known -based constructions of Souslin trees with various additional properties may be rendered as applications of … Continue reading

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Weak square and stationary reflection

Joint work with Gunter Fuchs. Abstract. It is well-known that the square principle ◻λ entails the existence of a non-reflecting stationary subset of λ+, whereas the weak square principle ◻λ does not. Here we show that if μcf(λ)<λ for all μ<λ, … Continue reading

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A forcing axiom deciding the generalized Souslin Hypothesis

Joint work with Chris Lambie-Hanson. Abstract. We derive a forcing axiom from the conjunction of square and diamond, and present a few applications, primary among them being the existence of super-Souslin trees. It follows that for every uncountable cardinal λ, … Continue reading

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A microscopic approach to Souslin-tree constructions. Part I

Joint work with Ari Meir Brodsky. Abstract.  We propose a parameterized proxy principle from which κ-Souslin trees with various additional features can be constructed, regardless of the identity of κ. We then introduce the microscopic approach, which is a simple … Continue reading

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Putting a diamond inside the square

Abstract. By a 35-year-old theorem of Shelah, ◻λ+(λ+) does not imply square-with-built-in-diamond_lambda for regular uncountable cardinals λ. Here, it is proved that ◻λ+(λ+) is equivalent to square-with-built-in-diamond_lambda for every singular cardinal λ. Downloads: Citation information: A. Rinot, Putting a diamond inside … Continue reading

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Many diamonds from just one

Recall Jensen’s diamond principle over a stationary subset S of a regular uncountable cardinal κ: there exists a sequence AααS such that {αSAα=Aα} is stationary for every Aκ. Equivalently, there exists a sequence $\langle … Continue reading

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Variations on diamond

Jensen’s diamond principle has many equivalent forms. The translation between these forms is often straight-forward, but there is one form whose equivalence to the usual form is somewhat surprising, and Devlin’s translation from one to the other, seems a little … Continue reading

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