English

A classification of incompleteness statements

Logic 2026-01-28 v3

Abstract

For which choices of X,Y,Z{Σ11,Π11}X,Y,Z\in\{\Sigma^1_1,\Pi^1_1\} does no sufficiently strong XX-sound and YY-definable extension theory prove its own ZZ-soundness? We give a complete answer, thereby delimiting the generalizations of G\"odel's second incompleteness theorem that hold within second-order arithmetic.

Keywords

Cite

@article{arxiv.2409.05973,
  title  = {A classification of incompleteness statements},
  author = {Henry Towsner and James Walsh},
  journal= {arXiv preprint arXiv:2409.05973},
  year   = {2026}
}
R2 v1 2026-06-28T18:39:06.201Z