English

A Cubical Language for Bishop Sets

Logic in Computer Science 2023-06-22 v5 Logic

Abstract

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.

Cite

@article{arxiv.2003.01491,
  title  = {A Cubical Language for Bishop Sets},
  author = {Jonathan Sterling and Carlo Angiuli and Daniel Gratzer},
  journal= {arXiv preprint arXiv:2003.01491},
  year   = {2023}
}
R2 v1 2026-06-23T14:01:57.677Z