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ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2018/iii/paper-121/1/vi/b/solution
Past exam of the mathematics course of the University of Cambridge 2018 iii Paper 121 1 vi b Solution by
Codex 0 Created 2026-10-03 Updated 2026-10-05
Let be the formula expressing cardinal number status:Ordinalhood and the assertion that a given set is a bijection between fixed sets are each expressible by a bounded formula in set theory. If regarded as a non-cardinal ordinal, a witnessing smaller ordinal and bijection would remain present and valid in . Ordinalhood itself is absolute between the transitive models. Thus implies : this is downward absoluteness of cardinalhood.
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