English

Failure of Normalization in Impredicative Type Theory with Proof-Irrelevant Propositional Equality

Logic in Computer Science 2023-06-22 v4 Programming Languages Logic

Abstract

Normalization fails in type theory with an impredicative universe of propositions and a proof-irrelevant propositional equality. The counterexample to normalization is adapted from Girard's counterexample against normalization of System F equipped with a decider for type equality. It refutes Werner's normalization conjecture [LMCS 2008].

Cite

@article{arxiv.1911.08174,
  title  = {Failure of Normalization in Impredicative Type Theory with Proof-Irrelevant Propositional Equality},
  author = {Andreas Abel and Thierry Coquand},
  journal= {arXiv preprint arXiv:1911.08174},
  year   = {2023}
}
R2 v1 2026-06-23T12:20:26.344Z