Difference between revisions of "Countable"
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| − | A set X is countable if and only if there is a bijection from X to the set of [[Natural Numbers]]. | + | A set X is countable if and only if there is a bijection from X to the set of [[Natural Numbers]]. Countable sets include the set of [[integer]]s and the set of [[rational number]]s. |
[[Category: Mathematics]] | [[Category: Mathematics]] | ||
Revision as of 10:53, March 27, 2007
A set X is countable if and only if there is a bijection from X to the set of Natural Numbers. Countable sets include the set of integers and the set of rational numbers.