Overlap Algebras: a Constructive Look at Complete Boolean Algebras

The notion of a complete Boolean algebra, although completely legitimate in constructive mathematics, fails to capture some natural structures such as the lattice of subsets of a given set. Sambin's notion of an overlap algebra, although classically equivalent to that of a complete Boolean alge...

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Main Authors: Francesco Ciraulo, Michele Contente
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2020-02-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/5417/pdf
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author Francesco Ciraulo
Michele Contente
author_facet Francesco Ciraulo
Michele Contente
author_sort Francesco Ciraulo
collection DOAJ
description The notion of a complete Boolean algebra, although completely legitimate in constructive mathematics, fails to capture some natural structures such as the lattice of subsets of a given set. Sambin's notion of an overlap algebra, although classically equivalent to that of a complete Boolean algebra, has powersets and other natural structures as instances. In this paper we study the category of overlap algebras as an extension of the category of sets and relations, and we establish some basic facts about mono-epi-isomorphisms and (co)limits; here a morphism is a symmetrizable function (with classical logic this is just a function which preserves joins). Then we specialize to the case of morphisms which preserve also finite meets: classically, this is the usual category of complete Boolean algebras. Finally, we connect overlap algebras with locales, and their morphisms with open maps between locales, thus obtaining constructive versions of some results about Boolean locales.
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spelling doaj.art-509390250e0a498395eafdd405f329872024-03-08T10:29:26ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742020-02-01Volume 16, Issue 110.23638/LMCS-16(1:13)20205417Overlap Algebras: a Constructive Look at Complete Boolean AlgebrasFrancesco CirauloMichele ContenteThe notion of a complete Boolean algebra, although completely legitimate in constructive mathematics, fails to capture some natural structures such as the lattice of subsets of a given set. Sambin's notion of an overlap algebra, although classically equivalent to that of a complete Boolean algebra, has powersets and other natural structures as instances. In this paper we study the category of overlap algebras as an extension of the category of sets and relations, and we establish some basic facts about mono-epi-isomorphisms and (co)limits; here a morphism is a symmetrizable function (with classical logic this is just a function which preserves joins). Then we specialize to the case of morphisms which preserve also finite meets: classically, this is the usual category of complete Boolean algebras. Finally, we connect overlap algebras with locales, and their morphisms with open maps between locales, thus obtaining constructive versions of some results about Boolean locales.https://lmcs.episciences.org/5417/pdfcomputer science - logic in computer sciencemathematics - logic
spellingShingle Francesco Ciraulo
Michele Contente
Overlap Algebras: a Constructive Look at Complete Boolean Algebras
Logical Methods in Computer Science
computer science - logic in computer science
mathematics - logic
title Overlap Algebras: a Constructive Look at Complete Boolean Algebras
title_full Overlap Algebras: a Constructive Look at Complete Boolean Algebras
title_fullStr Overlap Algebras: a Constructive Look at Complete Boolean Algebras
title_full_unstemmed Overlap Algebras: a Constructive Look at Complete Boolean Algebras
title_short Overlap Algebras: a Constructive Look at Complete Boolean Algebras
title_sort overlap algebras a constructive look at complete boolean algebras
topic computer science - logic in computer science
mathematics - logic
url https://lmcs.episciences.org/5417/pdf
work_keys_str_mv AT francescociraulo overlapalgebrasaconstructivelookatcompletebooleanalgebras
AT michelecontente overlapalgebrasaconstructivelookatcompletebooleanalgebras