{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,9,16]],"date-time":"2023-09-16T09:11:22Z","timestamp":1694855482526},"reference-count":8,"publisher":"Wiley","issue":"4-5","license":[{"start":{"date-parts":[[2018,10,18]],"date-time":"2018-10-18T00:00:00Z","timestamp":1539820800000},"content-version":"am","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2018,10,18]],"date-time":"2018-10-18T00:00:00Z","timestamp":1539820800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["1650069"],"award-info":[{"award-number":["1650069"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Mathematical Logic Qtrly"],"published-print":{"date-parts":[[2018,11]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Working in <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0001.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0001\" \/> (Intuitionistic analysis) we prove a strong, constructive connectedness property of the continuum: for any non\u2010empty sets, <jats:italic>A<\/jats:italic> and <jats:italic>B<\/jats:italic>, if <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0002.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0002\" \/> then <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0003.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0003\" \/> is non\u2010empty. It is well known that the intuitionistic continuum is <jats:italic>indecomposable<\/jats:italic>: if <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0004.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0004\" \/> and <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0005.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0005\" \/> then <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0006.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0006\" \/> or <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0007.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0007\" \/>, but this property is essentially negative\u2014equivalent to if <jats:italic>A<\/jats:italic>, <jats:italic>B<\/jats:italic> are non\u2010empty and <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0008.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0008\" \/> then <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0009.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0009\" \/>. Our connectedness property is positive; so, given <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0010.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0010\" \/>, <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0011.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0011\" \/>, and a witness to <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0012.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0012\" \/>, to prove our theorem we must construct a real number <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0013.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0013\" \/>. We can construct the needed real number using only Bishop's constructive mathematics (<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/malq201700057-math-0014.png\" xlink:title=\"urn:x-wiley:09425616:media:malq201700057:malq201700057-math-0014\" \/>) and a weak form of Brouwer's continuity principle (and the choice principles that come from the Brouwer\u2010Heyting\u2010Kolmogorov interpretation of quantifiers in constructive type theory). We also replace indecomposability by connectedness in some results of van Dalen that use additional intuitionistic axioms.<\/jats:p>","DOI":"10.1002\/malq.201700057","type":"journal-article","created":{"date-parts":[[2018,10,28]],"date-time":"2018-10-28T21:00:41Z","timestamp":1540760441000},"page":"387-394","update-policy":"http:\/\/dx.doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Connectedness of the continuum in intuitionistic mathematics"],"prefix":"10.1002","volume":"64","author":[{"given":"Mark","family":"Bickford","sequence":"first","affiliation":[{"name":"Department of Computer Science Cornell University Bill and Melinda Gates Hall, 107 Hoy Rd Ithaca NY 14853 United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2018,10,18]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-642-61667-9"},{"key":"e_1_2_9_3_1","first-page":"153","volume-title":"13th International Conference on Typed Lambda Calculi and Applications","author":"Escard\u00f3 M. 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