Journal of Symbolic Logic

The proof-theoretic analysis of transfinitely iterated quasi least fixed points

Dieter Probst

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The starting point of this article is an old question asked by Feferman in his paper on Hancock’s conjecture [6] about the strength of ID₁*. This theory is obtained from the well-known theory ID₁ by restricting fixed point induction to formulas that contain fixed point constants only positively. The techniques used to perform the proof-theoretic analysis of ID₁* also permit to analyze its transfinitely iterated variants IDα*. Thus, we eventually know that |\hat{ID}α| = |IDα*|.

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J. Symbolic Logic, Volume 71, Issue 3 (2006), 721-746.

First available in Project Euclid: 4 August 2006

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Fixed points Iteration Pseudo-hierarchies


Probst, Dieter. The proof-theoretic analysis of transfinitely iterated quasi least fixed points. J. Symbolic Logic 71 (2006), no. 3, 721--746. doi:10.2178/jsl/1154698573.

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