Failure of Normalization in Impredicative Type Theory with
Proof-Irrelevant Propositional EqualityArticle
Authors: Andreas Abel ; Thierry Coquand
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Andreas Abel;Thierry Coquand
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].
Loïc Pujet;Nicolas Tabareau, 2023, Impredicative Observational Equality, Proceedings of the ACM on Programming Languages, 7, POPL, pp. 2171-2196, 10.1145/3571739, https://doi.org/10.1145/3571739.
Loïc Pujet;Nicolas Tabareau, 2022, Observational equality: now for good, Proceedings of the ACM on Programming Languages, 6, POPL, pp. 1-27, 10.1145/3498693, https://doi.org/10.1145/3498693.