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Dedekind-infinite (Definition)

A set $ A$ is said to be Dedekind-infinite if there is an injective function $ f\colon\omega\to A$, where $ \omega$ denotes the set of natural numbers.

A Dedekind-infinite set is clearly infinite, and in ZFC it can be shown that a set is Dedekind-infinite if and only if it is infinite.

It is consistent with ZF that there is an infinite set that is not Dedekind-infinite. However, the existence of such a set requires the failure not just of the full Axiom of Choice, but even of the Axiom of Countable Choice.



"Dedekind-infinite" is owned by yark. [ full author list (2) | owner history (1) ]
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See Also: cardinality

Other names:  Dedekind infinite
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Cross-references: axiom of countable choice, axiom of choice, consistent, ZFC, infinite, natural numbers, injective function
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This is version 6 of Dedekind-infinite, born on 2002-01-03, modified 2006-04-22.
Object id is 1182, canonical name is DedekindInfinite.
Accessed 3662 times total.

Classification:
AMS MSC03E99 (Mathematical logic and foundations :: Set theory :: Miscellaneous)

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