On absolutely operations
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Displaying 1 – 8 of 8
On collections of almost disjoint families
Bohuslav Balcar, Petr Simon (1988)
Commentationes Mathematicae Universitatis Carolinae
On game ideals
Andrzej Rosłanowski (1990)
Colloquium Mathematicae
On iterated forcing for successors of regular cardinals
Todd Eisworth (2003)
Fundamenta Mathematicae
We investigate the problem of when ≤λ-support iterations of < λ-complete notions of forcing preserve λ⁺. We isolate a property- properness over diamonds-that implies λ⁺ is preserved and show that this property is preserved by λ-support iterations. Our condition is a relative of that presented by Rosłanowski and Shelah in [2]; it is not clear if the two conditions are equivalent. We close with an application of our technology by presenting a consistency result on uniformizing colorings of ladder...
On the existence of a -closed dense subset
Jindřich Zapletal (2010)
Commentationes Mathematicae Universitatis Carolinae
It is consistent with the axioms of set theory that there are two co-dense partial orders, one of them -closed and the other one without a -closed dense subset.
On the injectivity of Boolean algebras
Bernhard Banaschewski (1993)
Commentationes Mathematicae Universitatis Carolinae
The functor taking global elements of Boolean algebras in the topos of sheaves on a complete Boolean algebra is shown to preserve and reflect injectivity as well as completeness. This is then used to derive a result of Bell on the Boolean Ultrafilter Theorem in -valued set theory and to prove that (i) the category of complete Boolean algebras and complete homomorphisms has no non-trivial injectives, and (ii) the category of frames has no absolute retracts.
On Todorcevic orderings
Bohuslav Balcar, Tomáš Pazák, Egbert Thümmel (2015)
Fundamenta Mathematicae
The Todorcevic ordering 𝕋(X) consists of all finite families of convergent sequences in a given topological space X. Such an ordering was defined for the special case of the real line by S. Todorcevic (1991) as an example of a Borel ordering satisfying ccc that is not σ-finite cc and even need not have the Knaster property. We are interested in properties of 𝕋(X) where the space X is taken as a parameter. Conditions on X are given which ensure the countable chain condition and its stronger versions...
Open mappings on extremally disconnected compact spaces
Egbert Thümmel (2006)
Acta Universitatis Carolinae. Mathematica et Physica
Currently displaying 1 – 8 of 8
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