Countable Set

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An Countable Set is a set (with countable set members) that has a One-to-One Relation with the The N0 Natural Number Sequence.



  • (Wikipedia, 2015) ⇒ Retrieved:2015-6-1.
    • In mathematics, a countable set is a set with the same cardinality (number of elements) as some subset of the set of natural numbers. A countable set is either a finite set or a countably infinite set. Whether finite or infinite, the elements of a countable set can always be counted one at a time and, although the counting may never finish, every element of the set is associated with a natural number.

      Some authors use countable set to mean infinitely countable alone.[1] To avoid this ambiguity, the term at most countable may be used when finite sets are included and countably infinite, enumerable, or denumerable otherwise.

      The term countable set was originated by Georg Cantor who contrasted sets which are countable with those which are uncountable (a.k.a. nonenumerable and nondenumerable ). Today, countable sets are researched by a branch of mathematics called discrete mathematics.

  1. For an example of this usage see .