2-Coherent Internal Models of Homotopical Type Theory

Fuente: arXiv
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Main Author: Chen, Joshua
Format: Preprint
Published: 2025
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author Chen, Joshua
author_facet Chen, Joshua
contents The program of internal type theory seeks to develop the categorical model theory of dependent type theory using the language of dependent type theory itself. In the present work we study internal homotopical type theory by relaxing the notion of a category with families (cwf) to that of a wild, or precoherent higher cwf, and determine coherence conditions that suffice to recover properties expected of models of dependent type theory. The result is a definition of a split 2-coherent wild cwf, which admits as instances both the syntax and the "standard model" given by a universe type. This will allow us to give a straightforward internalization of the notion of a 2-coherent reflection of homotopical type theory in itself: namely as a 2-coherent wild cwf morphism from the syntax to the standard model. Our theory also easily specializes to give definitions of "low-dimensional" higher cwfs, and conjecturally includes the container higher model as a further instance.
format Preprint
id arxiv_https___arxiv_org_abs_2503_05790
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle 2-Coherent Internal Models of Homotopical Type Theory
Chen, Joshua
Logic in Computer Science
Category Theory
Logic
03B38, 03B70 (Primary) 18C50, 68Q55 (Secondary)
F.4.1; F.3.2; D.3.1
The program of internal type theory seeks to develop the categorical model theory of dependent type theory using the language of dependent type theory itself. In the present work we study internal homotopical type theory by relaxing the notion of a category with families (cwf) to that of a wild, or precoherent higher cwf, and determine coherence conditions that suffice to recover properties expected of models of dependent type theory. The result is a definition of a split 2-coherent wild cwf, which admits as instances both the syntax and the "standard model" given by a universe type. This will allow us to give a straightforward internalization of the notion of a 2-coherent reflection of homotopical type theory in itself: namely as a 2-coherent wild cwf morphism from the syntax to the standard model. Our theory also easily specializes to give definitions of "low-dimensional" higher cwfs, and conjecturally includes the container higher model as a further instance.
title 2-Coherent Internal Models of Homotopical Type Theory
topic Logic in Computer Science
Category Theory
Logic
03B38, 03B70 (Primary) 18C50, 68Q55 (Secondary)
F.4.1; F.3.2; D.3.1
url https://arxiv.org/abs/2503.05790