Partiality, revisited: the partiality monad as a quotient inductive-inductive type

Capretta's delay monad can be used to model partial computations, but it has the "wrong" notion of built-in equality, strong bisimilarity. An alternative is to quotient the delay monad by the "right" notion of equality, weak bisimilarity. However, recent work by Chapman et a...

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Main Authors: Altenkirch, Thorsten, Danielsson, Nils Anders, Kraus, Nicolai
Format: Article
Published: Springer Verlag 2017
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Online Access:https://eprints.nottingham.ac.uk/38095/
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author Altenkirch, Thorsten
Danielsson, Nils Anders
Kraus, Nicolai
author_facet Altenkirch, Thorsten
Danielsson, Nils Anders
Kraus, Nicolai
author_sort Altenkirch, Thorsten
building Nottingham Research Data Repository
collection Online Access
description Capretta's delay monad can be used to model partial computations, but it has the "wrong" notion of built-in equality, strong bisimilarity. An alternative is to quotient the delay monad by the "right" notion of equality, weak bisimilarity. However, recent work by Chapman et al. suggests that it is impossible to define a monad structure on the resulting construction in common forms of type theory without assuming (instances of) the axiom of countable choice. Using an idea from homotopy type theory - a higher inductive-inductive type - we construct a partiality monad without relying on countable choice. We prove that, in the presence of countable choice, our partiality monad is equivalent to the delay monad quotiented by weak bisimilarity. Furthermore we outline several applications.
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spelling nottingham-380952020-05-04T18:38:00Z https://eprints.nottingham.ac.uk/38095/ Partiality, revisited: the partiality monad as a quotient inductive-inductive type Altenkirch, Thorsten Danielsson, Nils Anders Kraus, Nicolai Capretta's delay monad can be used to model partial computations, but it has the "wrong" notion of built-in equality, strong bisimilarity. An alternative is to quotient the delay monad by the "right" notion of equality, weak bisimilarity. However, recent work by Chapman et al. suggests that it is impossible to define a monad structure on the resulting construction in common forms of type theory without assuming (instances of) the axiom of countable choice. Using an idea from homotopy type theory - a higher inductive-inductive type - we construct a partiality monad without relying on countable choice. We prove that, in the presence of countable choice, our partiality monad is equivalent to the delay monad quotiented by weak bisimilarity. Furthermore we outline several applications. Springer Verlag 2017-03-16 Article PeerReviewed Altenkirch, Thorsten, Danielsson, Nils Anders and Kraus, Nicolai (2017) Partiality, revisited: the partiality monad as a quotient inductive-inductive type. Lecture Notes in Computer Science, 10203 . pp. 534-549. ISSN 0302-9743 homotopy type theory quotient inductive-inductive type partiality partial computation https://link.springer.com/chapter/10.1007/978-3-662-54458-7_31 doi:10.1007/978-3-662-54458-7_31 doi:10.1007/978-3-662-54458-7_31
spellingShingle homotopy type theory
quotient inductive-inductive type
partiality
partial computation
Altenkirch, Thorsten
Danielsson, Nils Anders
Kraus, Nicolai
Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title_full Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title_fullStr Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title_full_unstemmed Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title_short Partiality, revisited: the partiality monad as a quotient inductive-inductive type
title_sort partiality, revisited: the partiality monad as a quotient inductive-inductive type
topic homotopy type theory
quotient inductive-inductive type
partiality
partial computation
url https://eprints.nottingham.ac.uk/38095/
https://eprints.nottingham.ac.uk/38095/
https://eprints.nottingham.ac.uk/38095/