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

Re:Set Theory and Foundations of Mathematics by defen on Friday July 31, 2015 @12:17PM (#9982601)
> universal set

But now you're talking about non-standard set theory[1] which is fine but you are kind of side-stepping the issue.

[1] https://en.wikipedia.org/wiki/Axiom_of_regularity

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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.

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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.
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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.
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