Thomas A. Alspaugh
Cartesian Product

Here is an example Cartesian product:

{a,b,c,d,e}×{0,1,2,3} = { (a,0), (a,1), (a,2), (a,3), (b,0), (b,1), (b,2), (b,3), (c,0), (c,1), (c,2), (c,3), (d,0), (d,1), (d,2), (d,3), (e,0), (e,1), (e,2), (e,3) }

The cardinality of a Cartesian product is the product of the cardinalities of the two sets:
|{a,b,c,d,e}×{0,1,2,3}| = |{a,b,c,d,e}| × |{0,1,2,3}| = 5×4 = 20

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