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Joined 2026-09-21 Message
Incoming links: Countably infinite set
Countable set Created 2026-09-24 Updated 2026-10-03
A countable set is a set that admits an injective function into the natural numbers. It is therefore either a finite set or a countably infinite set.
Infinite set 2026-10-03
An infinite set is a set with infinitely many elements. Equivalently, assuming the axiom of choice, it contains a countably infinite set.