Sir / Madam,

The total number of relations that can be defined from a set A to a set B

is the number of possible subsets of A × B. If n(A ) = p and n(B) = q, then

n (A × B) = pq and the total number of relations is 2^{pq }(we say).

However, doesn't 2^{pq}. also count the null set of ordered pairs as a relation? whether to count a null set of ordered pairs as a relation?

kindly enlighten me.

with regards

Aranga