A Generalized Algebraic Theory for Type Theory with Explicit Universe Polymorphism

Fuente: arXiv
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Hauptverfasser: Bezem, Marc, Coquand, Thierry, Dybjer, Peter, Escardó, Martín
Format: Preprint
Veröffentlicht: 2026
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author Bezem, Marc
Coquand, Thierry
Dybjer, Peter
Escardó, Martín
author_facet Bezem, Marc
Coquand, Thierry
Dybjer, Peter
Escardó, Martín
contents We present generalized algebraic theories corresponding to slightly modified versions of two of the type theories in our paper Type Theory with Explicit Universe Polymorphism. We first present a generalized algebraic theory for categories with families with extra structure corresponding to Martin-Lof type theory with an external tower of universes. We then present a generalized algebraic theory for level-indexed categories with families with extra structure corresponding to Martin-Lof type theory with explicit universe polymorphism: a theory with universe level judgments, internally indexed universes, and level-indexed products. In this way we get abstract characterizations of the two theories as initial models of their respective generalized algebraic theories. We thus abstract from details of the grammar and inference rules of the type theories and highlight their high-level structure. More broadly, the present work can be viewed as a case study of a uniform approach to categorical logic based on generalized algebraic theories and categories with families. We also discuss the relevance to Voevodsky's initiality conjecture project.
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id arxiv_https___arxiv_org_abs_2603_04010
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Generalized Algebraic Theory for Type Theory with Explicit Universe Polymorphism
Bezem, Marc
Coquand, Thierry
Dybjer, Peter
Escardó, Martín
Logic in Computer Science
We present generalized algebraic theories corresponding to slightly modified versions of two of the type theories in our paper Type Theory with Explicit Universe Polymorphism. We first present a generalized algebraic theory for categories with families with extra structure corresponding to Martin-Lof type theory with an external tower of universes. We then present a generalized algebraic theory for level-indexed categories with families with extra structure corresponding to Martin-Lof type theory with explicit universe polymorphism: a theory with universe level judgments, internally indexed universes, and level-indexed products. In this way we get abstract characterizations of the two theories as initial models of their respective generalized algebraic theories. We thus abstract from details of the grammar and inference rules of the type theories and highlight their high-level structure. More broadly, the present work can be viewed as a case study of a uniform approach to categorical logic based on generalized algebraic theories and categories with families. We also discuss the relevance to Voevodsky's initiality conjecture project.
title A Generalized Algebraic Theory for Type Theory with Explicit Universe Polymorphism
topic Logic in Computer Science
url https://arxiv.org/abs/2603.04010