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Minimal Upper Bounds for Sequences of Δ^1_(2n)-Degrees

Kechris, Alexander S. (1978) Minimal Upper Bounds for Sequences of Δ^1_(2n)-Degrees. Journal of Symbolic Logic, 43 (3). pp. 502-507. ISSN 0022-4812.

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It is proved here, assuming Projective Determinacy, that every ascending sequence of Δ^1_(2n)-degrees has a minimal strict upper bound but no least strict upper bound. This generalizes a result of Friedman for n = 1.

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Additional Information:© 1978, Association for Symbolic Logic. Received April 15, 1977. Research and preparation for this paper were partially supported by NSF Grants MPS75-07562 and MCS76-17254 respectively.
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MathSciNet ReviewMR0503788
Zentralblatt MATH Identifier0405.03019
Issue or Number:3
Record Number:CaltechAUTHORS:20130528-083000082
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Official Citation:Minimal Upper Bounds for Sequences of Δ^1_(2n)-Degree Alexander S. Kechris; 502-507
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38674
Deposited By: Ruth Sustaita
Deposited On:28 May 2013 15:41
Last Modified:03 Oct 2019 04:59

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