Cofinalities of countable ultraproducts: The existence theorem (Q908904)
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scientific article; zbMATH DE number 4135929
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Cofinalities of countable ultraproducts: The existence theorem |
scientific article; zbMATH DE number 4135929 |
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Cofinalities of countable ultraproducts: The existence theorem (English)
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1989
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The author shows that there exists an ultrafilter U on \(\omega\) such that the cofinality of the ultrapower \(^{\omega}\omega /U\) equals the cofinality of the minimal cardinality of any dominating family of \(^{\omega}\omega\). The coinitiality of the family of finite-to-one functions in this ultrapower is the same.
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ultrafilter
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cofinality
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ultrapower
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dominating family
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coinitiality
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finite-to-one functions
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