cardinality of a countable union

Let C be a countableMathworldPlanetmath collectionMathworldPlanetmath of countable sets. Then C is countable.

Title cardinality of a countable union
Canonical name CardinalityOfACountableUnion
Date of creation 2013-03-22 11:59:59
Last modified on 2013-03-22 11:59:59
Owner vampyr (22)
Last modified by vampyr (22)
Numerical id 5
Author vampyr (22)
Entry type Theorem
Classification msc 03E10
Related topic A_nAreCountableSoIsA_1XXA_nIfA_1