Where in math is the subset partial ordering used to describe one set as larger than another?<p>Diagonalization isn&#x27;t showing that a number in set A isn&#x27;t in set B - that&#x27;s obviously true for reals and integers, but it&#x27;s also true for rationals and integers.  It&#x27;s showing that there does not exist a mapping from B to A where there&#x27;s an element in B for each element in A.<p>We&#x27;re obviously not using the same definition of &quot;size&quot;.  I generally think in terms of cardinality, what are you thinking of?