$\undertilde {\delta }_2^1$ without sharps
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- by Sy D. Friedman and W. Hugh Woodin PDF
- Proc. Amer. Math. Soc. 124 (1996), 2211-2213 Request permission
Abstract:
We show that the supremum of the lengths of ${\underset {\sim }{\Delta }}^1_2$ prewellorderings of the reals can be $\omega _{2}$, with $\omega _{1}$ inaccessible to reals, assuming only the consistency of an inaccessible.References
- Sy D. Friedman, A large $\Pi ^1_2$ set, absolute for set forcings, Proc. Amer. Math. Soc. 122 (1994), no. 1, 253–256. MR 1231297, DOI 10.1090/S0002-9939-1994-1231297-3
- Friedman-Velickovic, $\Delta _1$-Definability (to appear).
- Martin, Descriptive Set Theory: Projective Sets, Handbook of Mathematical Logic, Studies in Logic and the Foundations of Mathematics 90, Barwise (editor), pp. 783–815.
- Steel-Welch, $\Sigma ^{1}_{3}$ Absoluteness and the Second Uniform Indiscernible, Israel Journal of Mathematics (to appear).
Additional Information
- Sy D. Friedman
- Affiliation: Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Address at time of publication: Equipe de Logique, Université de Paris 7, 2, Place Jussieu, 75251 Paris Cedex 05, France
- MR Author ID: 191285
- Email: sdf@math.mit.edu
- W. Hugh Woodin
- Affiliation: Department of Mathematics, University of California, Berkeley, California 94720
- Email: woodin@math.berkeley.edu
- Received by editor(s): September 22, 1994
- Received by editor(s) in revised form: February 6, 1995
- Additional Notes: Research supported by NSF contracts, nos. 9205530, 9322442.
- Communicated by: Andreas R. Blass
- © Copyright 1996 American Mathematical Society
- Journal: Proc. Amer. Math. Soc. 124 (1996), 2211-2213
- MSC (1991): Primary 03E15, 03E35, 03E55
- DOI: https://doi.org/10.1090/S0002-9939-96-03297-2
- MathSciNet review: 1322923