Re: Is {{}} a valid construct?

From: Neo <neo55592_at_hotmail.com>
Date: 6 Feb 2007 08:03:38 -0800
Message-ID: <1170777818.805732.66040@v45g2000cwv.googlegroups.com>

> A necessary precondition for getting unconfused is figuring out the difference between the empty set and the set containing the empty set.

Actually it is realizing that there is no set when there are no elements. But using your logic, for U = { {}, apple, orange} which of the following is the correct answer?

NOT {} = apple, orange
-or-
NOT {} = {}, apple, orange

One solution gives 2 elements and the other 3. Which count do you prefer? Received on Tue Feb 06 2007 - 10:03:38 CST