1. The Barwise-Schlipf theorem.
- Author
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Enayat, Ali and Schmerl, James H.
- Subjects
ARITHMETIC ,EVIDENCE - Abstract
In 1975 Barwise and Schlipf published a landmark paper whose main theorem asserts that a nonstandard model M of PA (Peano arithmetic) is recursively saturated iff M has an expansion that satisfies the subsystem Δ
1 1 −CA0 of second order arithmetic. In this paper we identify a crucial error in the Barwise-Schlipf proof of the right-to-left direction of the theorem, and we offer a correct proof of the problematic direction. [ABSTRACT FROM AUTHOR]- Published
- 2021
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