Axioms for Modelling Cubical Type Theory in a Topos

The homotopical approach to intensional type theory views proofs of equality as paths. We explore what is required of an object $I$ in a topos to give such a path-based model of type theory in which paths are just functions with domain $I$. Cohen, Coquand, Huber and M\"ortberg give such a model...

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Main Authors: Ian Orton, Andrew M. Pitts
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2018-12-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/4491/pdf
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author Ian Orton
Andrew M. Pitts
author_facet Ian Orton
Andrew M. Pitts
author_sort Ian Orton
collection DOAJ
description The homotopical approach to intensional type theory views proofs of equality as paths. We explore what is required of an object $I$ in a topos to give such a path-based model of type theory in which paths are just functions with domain $I$. Cohen, Coquand, Huber and M\"ortberg give such a model using a particular category of presheaves. We investigate the extent to which their model construction can be expressed in the internal type theory of any topos and identify a collection of quite weak axioms for this purpose. This clarifies the definition and properties of the notion of uniform Kan filling that lies at the heart of their constructive interpretation of Voevodsky's univalence axiom. (This paper is a revised and expanded version of a paper of the same name that appeared in the proceedings of the 25th EACSL Annual Conference on Computer Science Logic, CSL 2016.)
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spelling doaj.art-b389b69bda97409c912297d69e08e3672024-03-08T10:27:52ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742018-12-01Volume 14, Issue 410.23638/LMCS-14(4:23)20184491Axioms for Modelling Cubical Type Theory in a ToposIan OrtonAndrew M. PittsThe homotopical approach to intensional type theory views proofs of equality as paths. We explore what is required of an object $I$ in a topos to give such a path-based model of type theory in which paths are just functions with domain $I$. Cohen, Coquand, Huber and M\"ortberg give such a model using a particular category of presheaves. We investigate the extent to which their model construction can be expressed in the internal type theory of any topos and identify a collection of quite weak axioms for this purpose. This clarifies the definition and properties of the notion of uniform Kan filling that lies at the heart of their constructive interpretation of Voevodsky's univalence axiom. (This paper is a revised and expanded version of a paper of the same name that appeared in the proceedings of the 25th EACSL Annual Conference on Computer Science Logic, CSL 2016.)https://lmcs.episciences.org/4491/pdfcomputer science - logic in computer sciencef.4.1
spellingShingle Ian Orton
Andrew M. Pitts
Axioms for Modelling Cubical Type Theory in a Topos
Logical Methods in Computer Science
computer science - logic in computer science
f.4.1
title Axioms for Modelling Cubical Type Theory in a Topos
title_full Axioms for Modelling Cubical Type Theory in a Topos
title_fullStr Axioms for Modelling Cubical Type Theory in a Topos
title_full_unstemmed Axioms for Modelling Cubical Type Theory in a Topos
title_short Axioms for Modelling Cubical Type Theory in a Topos
title_sort axioms for modelling cubical type theory in a topos
topic computer science - logic in computer science
f.4.1
url https://lmcs.episciences.org/4491/pdf
work_keys_str_mv AT ianorton axiomsformodellingcubicaltypetheoryinatopos
AT andrewmpitts axiomsformodellingcubicaltypetheoryinatopos