> Yes -- in set theory sets can contain themselves
Which set theory? ZFC doesn't permit this.
Non-well-founded set theories are so non-standard that I think it's wrong, or at least misleading, to claim that unqualified "set theory" permits this.
Which set theory? ZFC doesn't permit this.
Non-well-founded set theories are so non-standard that I think it's wrong, or at least misleading, to claim that unqualified "set theory" permits this.
No comments yet.