{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,9,4]],"date-time":"2023-09-04T20:34:06Z","timestamp":1693859646401},"reference-count":0,"publisher":"Cambridge University Press (CUP)","issue":"6","license":[{"start":{"date-parts":[[2002,11,6]],"date-time":"2002-11-06T00:00:00Z","timestamp":1036540800000},"content-version":"unspecified","delay-in-days":5,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Funct. Prog."],"published-print":{"date-parts":[[2002,11]]},"abstract":"<jats:p>We systematically develop a functional program that solves the <jats:italic>countdown problem<\/jats:italic>, a numbers \ngame in which the aim is to construct arithmetic expressions satisfying certain constraints. \nStarting from a formal specification of the problem, we present a simple but inefficient \nprogram that solves the problem, and prove that this program is correct. We then use \nprogram fusion to calculate an equivalent but more efficient program, which is then further \nimproved by exploiting arithmetic properties.<\/jats:p>","DOI":"10.1017\/s0956796801004300","type":"journal-article","created":{"date-parts":[[2002,11,18]],"date-time":"2002-11-18T06:32:00Z","timestamp":1037601120000},"page":"609-616","source":"Crossref","is-referenced-by-count":6,"title":["The countdown problem"],"prefix":"10.1017","volume":"12","author":[{"given":"GRAHAM","family":"HUTTON","sequence":"first","affiliation":[]}],"member":"56","published-online":{"date-parts":[[2002,11,6]]},"container-title":["Journal of Functional Programming"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0956796801004300","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,5,6]],"date-time":"2019-05-06T20:24:07Z","timestamp":1557174247000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0956796801004300\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2002,11]]},"references-count":0,"journal-issue":{"issue":"6","published-print":{"date-parts":[[2002,11]]}},"alternative-id":["S0956796801004300"],"URL":"https:\/\/doi.org\/10.1017\/s0956796801004300","relation":{},"ISSN":["0956-7968","1469-7653"],"issn-type":[{"value":"0956-7968","type":"print"},{"value":"1469-7653","type":"electronic"}],"subject":[],"published":{"date-parts":[[2002,11]]}}}