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A NOTE ON PREDICATIVE ORDINAL ANALYSIS I: ITERATED COMPREHENSION AND TRANSFINITE INDUCTION

Published online by Cambridge University Press:  13 February 2019

SATO KENTARO*
Affiliation:
INSTITUTE OF COMPUTER SCIENCE UNIVERSITY OF BERN NEUBRÜCKSTRASSE 10 BERN 3012, SWITZERLANDE-mail: [email protected]

Abstract

We determine the proof-theoretic ordinals (i) of ${\cal C} - {\bf{TI}}[\alpha ]$, the transfinite induction along α, for any hyperarithmetical level ${\cal C}$, in the first order setting and (ii) of any combination of iterated arithmetical comprehension and ${\cal C} - {\bf{TI}}[\alpha ]$ for ${\cal C}\, \equiv \,{\rm{\Pi }}_k^i ,{\rm{\Sigma }}_k^i$ ($i\, = \,0,1$) in the second order setting.

Type
Articles
Copyright
Copyright © The Association for Symbolic Logic 2019 

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References

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