English

Wellfoundedness proof with the maximal distinguished set

Logic 2022-11-17 v1

Abstract

In arXiv:2208.12944 it is shown that an ordinal supN<ωψΩ1(εΩS+N+1)\sup_{N<\omega}\psi_{\Omega_{1}}(\varepsilon_{\Omega_{\mathbb{S}+N}+1}) is an upper bound for the proof-theoretic ordinal of a set theory KPr+(MΣ1V){\sf KP}\ell^{r}+(M\prec_{\Sigma_{1}}V). In this paper we show that a second order arithmetic Σ21\mboxCA+Π11\mboxCA0\Sigma^{1-}_{2}\mbox{-CA}+\Pi^{1}_{1}\mbox{-CA}_{0} proves the wellfoundedness up to ψΩ1(εΩS+N+1)\psi_{\Omega_{1}}(\varepsilon_{\Omega_{\mathbb{S}+N+1}}) for each NN. It is easy to interpret Σ21\mboxCA+Π11\mboxCA0\Sigma^{1-}_{2}\mbox{-CA}+\Pi^{1}_{1}\mbox{-CA}_{0} in KPr+(MΣ1V){\sf KP}\ell^{r}+(M\prec_{\Sigma_{1}}V).

Keywords

Cite

@article{arxiv.2211.08619,
  title  = {Wellfoundedness proof with the maximal distinguished set},
  author = {Toshiyasu Arai},
  journal= {arXiv preprint arXiv:2211.08619},
  year   = {2022}
}

Comments

arXiv admin note: text overlap with arXiv:1506.05280, arXiv:2112.09871, arXiv:2208.12944

R2 v1 2026-06-28T06:00:16.192Z