Results 151 to 160 of about 1,820 (180)

Number of Ultrafilters

1990
This cardinal function is rather easy to describe, at least if we do not try to go into the detail that we did for cellularity, for example. If A is a subalgebra or homomorphic image of B, then \( |Ult(A)| \leq |Ult(B)| \).
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Definability of measures and ultrafilters

Journal of Symbolic Logic, 1977
Nonprincipal ultrafilters are harder to define in ZFC, and harder to obtain in ZF + DC, than nonprincipal measures.The function μ from P(X) to the closed interval [0, 1] is a measure on X if μ. is finitely additive on disjoint sets and μ(X) = 1. (P is the power set.) μ is nonprincipal if μ ({x}) = 0 for each x Є X. μ is an ultrafilter if Range μ= {0, 1}
David Pincus, Robert Solovay
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Ultrafilters on spaces of partitions

Journal of Symbolic Logic, 1982
Qκλ. Pκλ the space of all < κ-sized subsets of λ, has provided numerous opportunities for the gainful employment of set theorists in recent years, thanks to its combinatorial richness and to its relationships with various large cardinals. In the spirit of Pκλ we offer the following definition:For κ ≤ λ both cardinals, Qκλ is the set of all ...
James M. Henle, William S. Zwicker
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Ultrafilters

The American Mathematical Monthly, 2008
Péter Komjáth, Vilmos Totik
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Concerning ultrafilters on ultrapowers

The Journal of Symbolic Logic, 1987
This paper concerns ultrafilters on a cardinal γ extending the filter of λ-closed, unbounded sets, λ < γ. The history of these ultrafilters is closely connected with that of the axiom of determinacy (AD). Solovay noticed first that, under AD, there was such an ultrafilter for γ = ℵ1; λ = ω.
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Ultrafilter selection and Corson compacta

Revista De La Real Academia De Ciencias Exactas, Fisicas Y Naturales - Serie A: Matematicas, 2022
Wieslaw Kubis, Robert Bonnet, Bonnet Robert   +2 more
exaly  

Strange ultrafilters

Archive for Mathematical Logic, 2018
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The ultrafilter number for singular cardinals

Acta Mathematica Hungarica, 2012
Shimon Garti, Saharon Shelah
exaly  

A small ultrafilter number at smaller cardinals

Archive for Mathematical Logic, 2019
Saharon Shelah, Dilip Raghavan
exaly  

Contamination of ultrapure water with bisphenol A leached from polysulfone ultrafilter

Talanta, 2012
Seungil Cho
exaly