Abstract
We show that that every countable model of PA has a conservative extension M with a subset Y such that a certain Σ1(Y)-formula defines in M a subset which is not r. e. relative to Y.
Original language | English |
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Pages (from-to) | 515-522 |
Number of pages | 8 |
Journal | Mathematical Logic Quarterly |
Volume | 41 |
Issue number | 4 |
DOIs | |
State | Published - 1995 |
Scopus Subject Areas
- Logic
Keywords
- Forcing
- Models of Peano Arithmetic
- Recursively enumerable
- Σ definable