Urutan Leksikografis

Alternatively, consider the functions "f" from an inversely well-ordered "X" to a well-ordered "Y" with minimum 0, restricted to those that are non-zero at only a finite subset of "X". The result is well-ordered. Correspondingly we can also consider a well-ordered "X" and apply lexicographical order where a higher "x" is a more significant position. This corresponds to exponentiation of ordinal numbers "Y". If "X" and "Y" are countable then the resulting set is also countable.