Proving Soundness of Extensional Normal-Form Bisimilarities

Normal-form bisimilarity is a simple, easy-to-use behavioral equivalence that relates terms in $\lambda$-calculi by decomposing their normal forms into bisimilar subterms. Moreover, it typically allows for powerful up-to techniques, such as bisimulation up to context, which simplify bisimulation pro...

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Main Authors: Dariusz Biernacki, Serguei Lenglet, Piotr Polesiuk
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2019-03-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/4041/pdf
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author Dariusz Biernacki
Serguei Lenglet
Piotr Polesiuk
author_facet Dariusz Biernacki
Serguei Lenglet
Piotr Polesiuk
author_sort Dariusz Biernacki
collection DOAJ
description Normal-form bisimilarity is a simple, easy-to-use behavioral equivalence that relates terms in $\lambda$-calculi by decomposing their normal forms into bisimilar subterms. Moreover, it typically allows for powerful up-to techniques, such as bisimulation up to context, which simplify bisimulation proofs even further. However, proving soundness of these relations becomes complicated in the presence of $\eta$-expansion and usually relies on ad hoc proof methods which depend on the language. In this paper we propose a more systematic proof method to show that an extensional normal-form bisimilarity along with its corresponding up to context technique are sound. We illustrate our technique with three calculi: the call-by-value $\lambda$-calculus, the call-by-value $\lambda$-calculus with the delimited-control operators shift and reset, and the call-by-value $\lambda$-calculus with the abortive control operators call/cc and abort. In the first two cases, there was previously no sound up to context technique validating the $\eta$-law, whereas no theory of normal-form bisimulations for a calculus with call/cc and abort has been presented before. Our results have been fully formalized in the Coq proof assistant.
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spelling doaj.art-d6163e609ac845ed9189c1d88a46fb822024-03-08T10:27:56ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742019-03-01Volume 15, Issue 110.23638/LMCS-15(1:31)20194041Proving Soundness of Extensional Normal-Form BisimilaritiesDariusz Biernackihttps://orcid.org/0000-0002-1477-4635Serguei LengletPiotr Polesiukhttps://orcid.org/0000-0002-7012-4346Normal-form bisimilarity is a simple, easy-to-use behavioral equivalence that relates terms in $\lambda$-calculi by decomposing their normal forms into bisimilar subterms. Moreover, it typically allows for powerful up-to techniques, such as bisimulation up to context, which simplify bisimulation proofs even further. However, proving soundness of these relations becomes complicated in the presence of $\eta$-expansion and usually relies on ad hoc proof methods which depend on the language. In this paper we propose a more systematic proof method to show that an extensional normal-form bisimilarity along with its corresponding up to context technique are sound. We illustrate our technique with three calculi: the call-by-value $\lambda$-calculus, the call-by-value $\lambda$-calculus with the delimited-control operators shift and reset, and the call-by-value $\lambda$-calculus with the abortive control operators call/cc and abort. In the first two cases, there was previously no sound up to context technique validating the $\eta$-law, whereas no theory of normal-form bisimulations for a calculus with call/cc and abort has been presented before. Our results have been fully formalized in the Coq proof assistant.https://lmcs.episciences.org/4041/pdfcomputer science - logic in computer sciencecomputer science - programming languages
spellingShingle Dariusz Biernacki
Serguei Lenglet
Piotr Polesiuk
Proving Soundness of Extensional Normal-Form Bisimilarities
Logical Methods in Computer Science
computer science - logic in computer science
computer science - programming languages
title Proving Soundness of Extensional Normal-Form Bisimilarities
title_full Proving Soundness of Extensional Normal-Form Bisimilarities
title_fullStr Proving Soundness of Extensional Normal-Form Bisimilarities
title_full_unstemmed Proving Soundness of Extensional Normal-Form Bisimilarities
title_short Proving Soundness of Extensional Normal-Form Bisimilarities
title_sort proving soundness of extensional normal form bisimilarities
topic computer science - logic in computer science
computer science - programming languages
url https://lmcs.episciences.org/4041/pdf
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AT sergueilenglet provingsoundnessofextensionalnormalformbisimilarities
AT piotrpolesiuk provingsoundnessofextensionalnormalformbisimilarities