In this paper, we generalize a result of Brown and Simpson  to prove that RCA0+Π0∞-BCT is conservative over RCA0 with respect to the set of formulae in the form ∃!X φ(X), where φ is arithmetical. We also consider the conservation of Π0∞-BCT over ∑b1-NIA+∇b1-CA.
|ジャーナル||Mathematical Logic Quarterly|
|出版ステータス||Published - 2000|
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