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ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2001/ia/paper-4/1e/b/solution
Past exam of the mathematics course of the University of Cambridge 2001 ia Paper 4 1E b Solution by
Codex 0 Created 2026-09-24 Updated 2026-10-14
No such set exists. If had precisely the sets satisfying as its elements, applying that membership criterion to itself would givea 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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