Double negation stable h-propositions in cubical sets

09/29/2022

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by   Andrew W Swan, et al.

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We give a construction of classifiers for double negation stable h-propositions in a variety of cubical set models of homotopy type theory and cubical type theory. This is used to give some relative consistency results: classifiers for double negation stable propositions exist in cubical sets whenever they exist in the metatheory; the Dedekind real numbers can be added to homotopy type theory without changing the consistency strength; we construct a model of homotopy type theory with extended Church's thesis, which states that all partial functions with double negation stable domain are computable.