Open Access
2002 Definability of Initial Segments
Saharon Shelah, Akito Tsuboi
Notre Dame J. Formal Logic 43(2): 65-73 (2002). DOI: 10.1305/ndjfl/1071509428


In any nonstandard model of Peano arithmetic, the standard part is not first-order definable. But we show that in some model the standard part is definable as the unique solution of a formula $\varphi(P)$, where P is a unary predicate variable.


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Saharon Shelah. Akito Tsuboi. "Definability of Initial Segments." Notre Dame J. Formal Logic 43 (2) 65 - 73, 2002.


Published: 2002
First available in Project Euclid: 15 December 2003

zbMATH: 1082.03038
MathSciNet: MR2033316
Digital Object Identifier: 10.1305/ndjfl/1071509428

Primary: 03C62 , 03H15
Secondary: 03C55

Keywords: absoluteness , definability , Peano Arithmetic

Rights: Copyright © 2002 University of Notre Dame

Vol.43 • No. 2 • 2002
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