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| Main Author: | |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2408.10367 |
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Table of Contents:
- We use forcing over admissible sets to show that, for every ordinal $α$ in a club $C\subsetω_1$, there are copies of $α$ such that the isomorphism between them is not computable in the join of the complete $Π^1_1$ set relative to each copy separately. Assuming $\mathsf{V=L}$, this is close to optimal; on the other hand, assuming large cardinals the same (and more) holds for every projective functional.