Nullary Cartesian Product
Consider the general definition of the Cartesian product:
If I is empty, the only satisfying g is the empty function :
Thus, the cardinality of the Cartesian product of no sets is 1.
Under the perhaps more familiar n-tuple interpretation,
that is, the singleton set containing the empty tuple. Note that in both representations the empty product has cardinality 1.
Read more about this topic: Empty Product
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