English

Patterns of resemblance and Bachmann-Howard fixed points

Logic 2021-01-07 v2

Abstract

Timothy Carlson's patterns of resemblance employ the notion of Σ1\Sigma_1-elementarity to describe large computable ordinals. It has been conjectured that a relativization of these patterns to dilators leads to an equivalence with Π11\Pi^1_1-comprehension (Question 27 of A. Montalb\'an's "Open questions in reverse mathematics", Bull. Symb. Log. 17(3)2011, 431-454). In the present paper we prove this conjecture. The crucial direction (towards Π11\Pi^1_1-comprehension) is reduced to a previous result of the author, which is concerned with relativizations of the Bachmann-Howard ordinal.

Keywords

Cite

@article{arxiv.2012.10292,
  title  = {Patterns of resemblance and Bachmann-Howard fixed points},
  author = {Anton Freund},
  journal= {arXiv preprint arXiv:2012.10292},
  year   = {2021}
}
R2 v1 2026-06-23T21:04:45.444Z