On Apr 12, 2008, at 17:37 , Moritz Lenz wrote:
[EMAIL PROTECTED] wrote:Technically the Cartesian cross operator doesn't have an identity value.It has. The set which contains only the emty set, or in perl terms ([]);
If (a, b) denotes an ordered pair you get
{0, 1} X {{}} = {(0, {}), (1, {})}
which, you see, is different from {0, 1}. They have different
elements. The fact that there's a clear mapping that sort of
identifies them has nothing to do with set equality.
-- fxn
