Displaying similar documents to “A new construction of non-constructible Δ 1 3 subset of ω”

A tree axiom.

Kurepa, Đuro (1985)

Publications de l'Institut Mathématique. Nouvelle Série

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Rudin's Dowker space in the extension with a Suslin tree

Teruyuki Yorioka (2008)

Fundamenta Mathematicae

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We introduce a generalization of a Dowker space constructed from a Suslin tree by Mary Ellen Rudin, and the rectangle refining property for forcing notions, which modifies the one for partitions due to Paul B. Larson and Stevo Todorčević and is stronger than the countable chain condition. It is proved that Martin's Axiom for forcing notions with the rectangle refining property implies that every generalized Rudin space constructed from Aronszajn trees is non-Dowker, and that the same...

Planting Kurepa trees and killing Jech-Кunen trees in a model by using one inaccessible cardinal

Saharon Shelah, R. Jin (1992)

Fundamenta Mathematicae

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By an ω 1 - tree we mean a tree of power ω 1 and height ω 1 . Under CH and 2 ω 1 > ω 2 we call an ω 1 -tree a Jech-Kunen tree if it has κ-many branches for some κ strictly between ω 1 and 2 ω 1 . In this paper we prove that, assuming the existence of one inaccessible cardinal, (1) it is consistent with CH plus 2 ω 1 > ω 2 that there exist Kurepa trees and there are no Jech-Kunen trees, which answers a question of [Ji2], (2) it is consistent with CH plus 2 ω 1 = ω 4 that there only exist Kurepa trees with ω 3 -many branches, which answers...

The Tree Property at ω₂ and Bounded Forcing Axioms

Sy-David Friedman, Víctor Torres-Pérez (2015)

Bulletin of the Polish Academy of Sciences. Mathematics

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We prove that the Tree Property at ω₂ together with BPFA is equiconsistent with the existence of a weakly compact reflecting cardinal, and if BPFA is replaced by BPFA(ω₁) then it is equiconsistent with the existence of just a weakly compact cardinal. Similarly, we show that the Special Tree Property for ω₂ together with BPFA is equiconsistent with the existence of a reflecting Mahlo cardinal, and if BPFA is replaced by BPFA(ω₁) then it is equiconsistent with the existence of just a Mahlo...