Multimodal Dependent Type Theory

We introduce MTT, a dependent type theory which supports multiple modalities. MTT is parametrized by a mode theory which specifies a collection of modes, modalities, and transformations between them. We show that different choices of mode theory allow us to use the same type theory to compute and re...

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Main Authors: Daniel Gratzer, G. A. Kavvos, Andreas Nuyts, Lars Birkedal
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2021-07-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/7571/pdf
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author Daniel Gratzer
G. A. Kavvos
Andreas Nuyts
Lars Birkedal
author_facet Daniel Gratzer
G. A. Kavvos
Andreas Nuyts
Lars Birkedal
author_sort Daniel Gratzer
collection DOAJ
description We introduce MTT, a dependent type theory which supports multiple modalities. MTT is parametrized by a mode theory which specifies a collection of modes, modalities, and transformations between them. We show that different choices of mode theory allow us to use the same type theory to compute and reason in many modal situations, including guarded recursion, axiomatic cohesion, and parametric quantification. We reproduce examples from prior work in guarded recursion and axiomatic cohesion, thereby demonstrating that MTT constitutes a simple and usable syntax whose instantiations intuitively correspond to previous handcrafted modal type theories. In some cases, instantiating MTT to a particular situation unearths a previously unknown type theory that improves upon prior systems. Finally, we investigate the metatheory of MTT. We prove the consistency of MTT and establish canonicity through an extension of recent type-theoretic gluing techniques. These results hold irrespective of the choice of mode theory, and thus apply to a wide variety of modal situations.
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spelling doaj.art-07e0c9691a85467f9ebe85fa9649460a2024-03-08T10:35:15ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742021-07-01Volume 17, Issue 310.46298/lmcs-17(3:11)20217571Multimodal Dependent Type TheoryDaniel Gratzerhttps://orcid.org/0000-0003-1944-0789G. A. KavvosAndreas Nuytshttps://orcid.org/0000-0002-1571-5063Lars BirkedalWe introduce MTT, a dependent type theory which supports multiple modalities. MTT is parametrized by a mode theory which specifies a collection of modes, modalities, and transformations between them. We show that different choices of mode theory allow us to use the same type theory to compute and reason in many modal situations, including guarded recursion, axiomatic cohesion, and parametric quantification. We reproduce examples from prior work in guarded recursion and axiomatic cohesion, thereby demonstrating that MTT constitutes a simple and usable syntax whose instantiations intuitively correspond to previous handcrafted modal type theories. In some cases, instantiating MTT to a particular situation unearths a previously unknown type theory that improves upon prior systems. Finally, we investigate the metatheory of MTT. We prove the consistency of MTT and establish canonicity through an extension of recent type-theoretic gluing techniques. These results hold irrespective of the choice of mode theory, and thus apply to a wide variety of modal situations.https://lmcs.episciences.org/7571/pdfcomputer science - logic in computer science
spellingShingle Daniel Gratzer
G. A. Kavvos
Andreas Nuyts
Lars Birkedal
Multimodal Dependent Type Theory
Logical Methods in Computer Science
computer science - logic in computer science
title Multimodal Dependent Type Theory
title_full Multimodal Dependent Type Theory
title_fullStr Multimodal Dependent Type Theory
title_full_unstemmed Multimodal Dependent Type Theory
title_short Multimodal Dependent Type Theory
title_sort multimodal dependent type theory
topic computer science - logic in computer science
url https://lmcs.episciences.org/7571/pdf
work_keys_str_mv AT danielgratzer multimodaldependenttypetheory
AT gakavvos multimodaldependenttypetheory
AT andreasnuyts multimodaldependenttypetheory
AT larsbirkedal multimodaldependenttypetheory