Abstract
In this note the proof-theoretic ordinal of the well-ordering principle for the normal functions \(\mathsf {g}\) on ordinals is shown to be equal to the least fixed point of \(\mathsf {g}\). Moreover corrections to the previous paper (Arai in Arch Math Log 57:649–664, 2017) are made.
Similar content being viewed by others
References
Afshari, B., Rathjen, M.: Reverse mathematics and well-ordering principles: a pilot study. Ann. Pure Appl. Log. 160, 231–237 (2009)
Arai, T.: Some results on cut-elimination, provable well-orderings, induction and reflection. Ann. Pure Appl. Log. 95, 93–184 (1998)
Arai, T.: Derivatives of normal functions and \(\omega \)-models. Arch. Math. Log. 57, 649–664 (2017)
Girard, J.-Y.: Proof Theory and Logical Complexity, vol. 1. Bibliopolis, Napoli (1987)
Marcone, A., Montalbán, A.: The Veblen functions for computability theorists. J. Symb. Log. 76, 575–602 (2011)
Rathjen, M.: \(\omega \)-models and well-ordering principles. In: Tennant, N. (ed.) IFoundational Adventures: Essays in Honor of Harvey M. Friedman, pp. 179–212. College Publications, London (2014)
Rathjen, M., Weiermann, A.: Reverse mathematics and well-ordering principles. In: Cooper, S., Sorbi, A. (eds.) Computability in Context: Computation and Logic in the Real World, pp. 351–370. Imperial College Press, London (2011)
Schütte, K.: Proof Theory. Springer, Berlin (1977)
Simpson, S.G.: Subsystems of Second Order Arithmetic, 2nd Edition, Perspectives in Logic. Cambridge UP, Cambridge (2009)
Takeuti, G.: A remark on Gentzen’s paper “Beweibarkeit und Unbeweisbarkeit von Anfangsfällen der transfiniten Induktion in der reinen Zahlentheorie”. Proc. Jpn. Acad. 39, 263–269 (1963)
Takeuti, G.: Proof Theory, 2nd edn. North-Holland, Amsterdam (1987)
Acknowledgements
I’d like to thank A. Freund for pointing out a flaw in [3], and the anonymous referee for a careful reading and helpful suggestions.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Arai, T. Proof-theoretic strengths of the well-ordering principles. Arch. Math. Logic 59, 257–275 (2020). https://doi.org/10.1007/s00153-019-00689-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00153-019-00689-4