Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2001/ia/paper-4/1e/b/solution

No such set exists. If had precisely the sets satisfying as its elements, applying that membership criterion to itself would give
a contradiction. This is Russell's paradox. It rules out this unrestricted universal collection; a set whose elements happen not to contain themselves is perfectly possible, for example the empty set.

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