A Cubical Language for Bishop Sets

We present XTT, a version of Cartesian cubical type theory specialized for Bishop sets \`a la Coquand, in which every type enjoys a definitional version of the uniqueness of identity proofs. Using cubical notions, XTT reconstructs many of the ideas underlying Observational Type Theory, a version of...

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Bibliographic Details
Main Authors: Jonathan Sterling, Carlo Angiuli, Daniel Gratzer
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2022-03-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/9069/pdf
Description
Summary:We present XTT, a version of Cartesian cubical type theory specialized for Bishop sets \`a la Coquand, in which every type enjoys a definitional version of the uniqueness of identity proofs. Using cubical notions, XTT reconstructs many of the ideas underlying Observational Type Theory, a version of intensional type theory that supports function extensionality. We prove the canonicity property of XTT (that every closed boolean is definitionally equal to a constant) using Artin gluing.
ISSN:1860-5974