latter statement, the letters "A", "B", "C"
signify category "objects", domains, sets, spaces,
or whatever you prefer to call them, "x" signifies
the "cartesian product" of these kinds of domains,
and the expression of the form "[X -&gt; Y]" denotes
the "function space" [X -&gt; Y] that contains "all",
suitably restricted, functions from X to Y.  Also,
the sign "~=~" is supposed to mean "isomorphic to".

¤~~~~~~~~~¤~~~~~~~~~¤~CITATION~¤~~~~~~~~~¤~~~~~~~~~¤

"A proof in standard first order logic":

| 