Author Archives: Assaf Rinot

Sums of triples in Abelian groups

Joint work with Ido Feldman. Abstract. Motivated by a problem in additive Ramsey theory, we extend Todorcevic’s partitions of three-dimensional combinatorial cubes to handle additional three-dimensional objects. As a corollary, we get that if the continuum hypothesis fails, then for … Continue reading

Posted in Groups, Partition Relations | Tagged , , , , , | 1 Comment

A club guessing toolbox I

Joint work with Tanmay Inamdar. Abstract. Club guessing principles were introduced by Shelah as a weakening of Jensen’s diamond. Most spectacularly, they were used to prove Shelah’s ZFC bound on the power of the first singular cardinal. These principles have … Continue reading

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

Ramsey theory over partitions II: Negative Ramsey relations and pump-up theorems

Joint work with Menachem Kojman and Juris Steprāns. Abstract. In this series of papers, we advance Ramsey theory of colorings over partitions. In this part, we concentrate on anti-Ramsey relations, or, as they are better known, strong colorings, and in … Continue reading

Posted in Partition Relations, Publications | Tagged , , | 1 Comment

A new small Dowker space

Joint work with Roy Shalev and Stevo Todorcevic. Abstract. It is proved that if there exists a Luzin set, or if either the stick principle or (b) hold, then an instance of the guessing principle AD holds at the … Continue reading

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

Was Ulam right? II: Small width and general ideals

Joint work with Tanmay Inamdar. Abstract. We continue our study of Sierpinski-type colourings. In contrast to the prequel paper, we focus here on colourings for ideals stratified by their completeness degree. In particular, improving upon Ulam’s theorem and its extension … Continue reading

Posted in Partition Relations, Publications | Tagged , , , , , , , | 1 Comment

MFO workshop in Set Theory, January 2022

I gave an invited talk at the Set Theory meeting in Obwerwolfach, January 2022. Talk Title: A dual of Juhasz’ question Abstract: Juhasz asked whether implies the existence of a Souslin tree. Here we settle the dual problem of … Continue reading

Posted in Invited Talks | Tagged , | Comments Off on MFO workshop in Set Theory, January 2022

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

Posted in Partition Relations | Tagged , | 1 Comment

Sigma-Prikry forcing III: Down to Aleph_omega

Joint work with Alejandro Poveda and Dima Sinapova. Abstract. We prove the consistency of the failure of the singular cardinals hypothesis at ω together with the reflection of all stationary subsets of ω+1. This shows that two classical results of … Continue reading

Posted in Compactness, Publications, Singular Cardinals Combinatorics | Tagged , , | 1 Comment

Was Ulam right? I: Basic theory and subnormal ideals

Joint work with Tanmay Inamdar. Abstract. We introduce various coloring principles which generalize the so-called onto mapping principle of Sierpinski to larger cardinals and general ideals. We prove that these principles capture the notion of an Ulam matrix and allow … Continue reading

Posted in Partition Relations | Tagged , , , , , , , , , , , | 1 Comment

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

Posted in Partition Relations, Publications | Tagged , , , , , , , , | 1 Comment