Definition:Co-Countable Set
(Redirected from Definition:Cocountable)
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Definition
Let $S$ be a set, and let $A \subseteq S$.
Then $A$ is said to be co-countable (in $S$) if and only if its relative complement $\complement_S \left({A}\right)$ is countable.
Also known as
Sometimes the hyphen is omitted, yielding cocountable.