News for hackers. Stuff that matters.

A comment on Set Theory and Foundations of Mathematics. Parent comment

Re:Set Theory and Foundations of Mathematics by Shaniqua on Friday July 31, 2015 @12:38PM (#9982721)
Well, it's not that difficult to fix it in ZF.

If you define S to be S = {x in U: x not in x}, then it simply means S is not in U.

[ Parent | on HN ]
Re:Set Theory and Foundations of Mathematics by defen on Friday July 31, 2015 @01:32PM (#9983032)
There is no U in ZF so I really don't understand what you are saying.
[ Parent | on HN ]
Re:Set Theory and Foundations of Mathematics by Shaniqua on Friday July 31, 2015 @01:57PM (#9983218)
You can call U anything you want. It's by axiom schema of specification: for any set A, there some set B with a set C in B iff C in A.
[ Parent | on HN ]