Formalising Inductive and Coinductive Containers

Fuente: arXiv
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Autori principali: Damato, Stefania, Altenkirch, Thorsten, Ljungström, Axel
Natura: Preprint
Pubblicazione: 2024
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author Damato, Stefania
Altenkirch, Thorsten
Ljungström, Axel
author_facet Damato, Stefania
Altenkirch, Thorsten
Ljungström, Axel
contents Containers capture the concept of strictly positive data types in programming. The original development of containers is done in the internal language of locally cartesian closed categories (LCCCs) with disjoint coproducts and W-types, and uniqueness of identity proofs (UIP) is implicitly assumed throughout. Although it is claimed that these developments can also be interpreted in extensional Martin-Löf type theory, this interpretation is not made explicit. In this paper, we present a formalisation of the results that 'containers preserve least and greatest fixed points' in Cubical Agda, thereby giving a formulation in intensional type theory. Our proofs do not make use of UIP and thereby generalise the original results from talking about container functors on Set to container functors on the wild category of types. Our main incentive for using Cubical Agda is that its path type restores the equivalence between bisimulation and coinductive equality. Thus, besides developing container theory in a more general setting, we also demonstrate the usefulness of Cubical Agda's path type to coinductive proofs.
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id arxiv_https___arxiv_org_abs_2409_02603
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Formalising Inductive and Coinductive Containers
Damato, Stefania
Altenkirch, Thorsten
Ljungström, Axel
Logic in Computer Science
Logic
Containers capture the concept of strictly positive data types in programming. The original development of containers is done in the internal language of locally cartesian closed categories (LCCCs) with disjoint coproducts and W-types, and uniqueness of identity proofs (UIP) is implicitly assumed throughout. Although it is claimed that these developments can also be interpreted in extensional Martin-Löf type theory, this interpretation is not made explicit. In this paper, we present a formalisation of the results that 'containers preserve least and greatest fixed points' in Cubical Agda, thereby giving a formulation in intensional type theory. Our proofs do not make use of UIP and thereby generalise the original results from talking about container functors on Set to container functors on the wild category of types. Our main incentive for using Cubical Agda is that its path type restores the equivalence between bisimulation and coinductive equality. Thus, besides developing container theory in a more general setting, we also demonstrate the usefulness of Cubical Agda's path type to coinductive proofs.
title Formalising Inductive and Coinductive Containers
topic Logic in Computer Science
Logic
url https://arxiv.org/abs/2409.02603