Relatively Recursively Enumerable Versus Relatively Σ1 in Models of Peano Arithmetic

Grzegorz J. Michalski

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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 languageEnglish
Pages (from-to)515-522
Number of pages8
JournalMathematical Logic Quarterly
Volume41
Issue number4
DOIs
StatePublished - 1995

Scopus Subject Areas

  • Logic

Keywords

  • Forcing
  • Models of Peano Arithmetic
  • Recursively enumerable
  • Σ definable

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