Tag Archives: Minimal Walks

Walks on uncountable ordinals and non-structure theorems for higher Aronszajn lines

Joint work with Tanmay Inamdar. Abstract. We investigate global structural properties of linear orders of a fixed infinite size. It is classical that the countable linear orders and the continuum-sized orders exhibit contrasting behaviours. Modern results show that strong extensions … Continue reading

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Complicated colorings, revisited

Joint work with Jing Zhang. Abstract. In a paper from 1997, Shelah asked whether Pr1(λ+,λ+,λ+,λ) holds for every inaccessible cardinal λ. Here, we prove that an affirmative answer follows from ◻(λ+).  Furthermore, we establish that for every pair χ<κ of … 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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Transformations of the transfinite plane

Joint work with Jing Zhang. Abstract. We study the existence of transformations of the transfinite plane that allow one to reduce Ramsey-theoretic statements concerning uncountable Abelian groups into classical partition relations for uncountable cardinals. To exemplify: we prove that for every … Continue reading

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11th Young Set Theory Workshop, June 2018

I gave a 4-lecture tutorial at the 11th Young Set Theory Workshop, Lausanne, June 2018. Title: In praise of C-sequences. Abstract. Ulam and Solovay showed that any stationary set may be split into two. Is it also the case that … Continue reading

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6th European Set Theory Conference, July 2017

I gave a 3-lecture tutorial at the 6th European Set Theory Conference in Budapest, July 2017. Title: Strong colorings and their applications. Abstract. Consider the following questions. Is the product of two κ-cc partial orders again κ-cc? Does there exist … Continue reading

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Distributive Aronszajn trees

Joint work with Ari Meir Brodsky. Abstract.  Ben-David and Shelah proved that if λ is a singular strong-limit cardinal and 2λ=λ+, then ◻λ entails the existence of a λ-distributive λ+-Aronszajn tree. Here, it is proved that the same conclusion remains … Continue reading

Posted in Publications, Squares and Diamonds | Tagged , , , , , , , , , | 1 Comment

Square with built-in diamond-plus

Joint work with Ralf Schindler. Abstract. We formulate combinatorial principles that combine the square principle with various strong forms of diamond, and prove that the strongest amongst them holds in L for every infinite cardinal. As an application, we prove that … Continue reading

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Chain conditions of products, and weakly compact cardinals

Abstract.  The history of productivity of the κ-chain condition in partial orders, topological spaces, or Boolean algebras is surveyed, and its connection to the set-theoretic notion of a weakly compact cardinal is highlighted. Then, it is proved that for every … Continue reading

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Complicated colorings

Abstract. If λ,κ are regular cardinals, λ>κ+, and Eκλ admits a nonreflecting stationary set, then Pr1(λ,λ,λ,κ) holds. (Recall that  Pr1(λ,λ,λ,κ) asserts the existence of  a coloring d:[λ]2λ such that for any family A[λ]<κ of size λ, consisting of pairwise … Continue reading

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