Evitable iterates of the consistency operator
Abstract
Let's fix a reasonable subsystem of arithmetic; why are natural extensions of pre-well-ordered by consistency strength? In previous work, an approach to this question was proposed. The goal of this work was to classify the recursive functions that are monotone with respect to the Lindenabum algebra of . According to an optimistic conjecture, roughly, every such function must be equivalent to an iterate of the consistency operator in the limit. In previous work the author established the first case of this optimistic conjecture; roughly, every recursive monotone function is either as weak as the identity operator in the limit or as strong as in the limit. Yet in this note we prove that this optimistic conjecture fails already at the next step; there are recursive monotone functions that are neither as weak as in the limit nor as strong as in the limit. In fact, for every , we produce a function that is cofinally as strong as yet cofinally as weak as .
Keywords
Cite
@article{arxiv.2202.01174,
title = {Evitable iterates of the consistency operator},
author = {James Walsh},
journal= {arXiv preprint arXiv:2202.01174},
year = {2022}
}