{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T22:43:09Z","timestamp":1784241789868,"version":"3.55.0"},"reference-count":1,"publisher":"Cambridge University Press (CUP)","issue":"2","license":[{"start":{"date-parts":[[2014,3,12]],"date-time":"2014-03-12T00:00:00Z","timestamp":1394582400000},"content-version":"unspecified","delay-in-days":23638,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. symb. log."],"published-print":{"date-parts":[[1949,6,23]]},"abstract":"<jats:p>Emil Post has shown that the word problem for Thue systems is unsolvable. A Thue system is a system of strings of letters <jats:italic>x<\/jats:italic><jats:sub>1<\/jats:sub>, <jats:italic>x<\/jats:italic><jats:sub>2<\/jats:sub>, \u2026, <jats:italic>x<\/jats:italic><jats:sub>r<\/jats:sub>, where a <jats:italic>string<\/jats:italic> or <jats:italic>word<\/jats:italic> is either void or a succession of letters <jats:italic>a<\/jats:italic><jats:sub>1<\/jats:sub><jats:italic>a<\/jats:italic><jats:sub>2<\/jats:sub> \u2026 <jats:italic>a<\/jats:italic><jats:sub>t<\/jats:sub> with each <jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub> some <jats:italic>x<\/jats:italic><jats:sub>i<\/jats:sub>. We are given a finite number of pairs of strings <jats:italic>A<\/jats:italic><jats:sub>i<\/jats:sub>, <jats:italic>B<\/jats:italic><jats:sub>i<\/jats:sub><jats:italic>i<\/jats:italic> = 1, \u2026, <jats:italic>m<\/jats:italic>. Operations in the Thue system consist of the replacements or \u201cproductions.\u201d<\/jats:p>","DOI":"10.2307\/2266511","type":"journal-article","created":{"date-parts":[[2006,5,6]],"date-time":"2006-05-06T19:05:25Z","timestamp":1146942325000},"page":"115-118","source":"Crossref","is-referenced-by-count":14,"title":["The word problem for semigroups with two generators"],"prefix":"10.1017","volume":"14","author":[{"suffix":"Jr.","given":"Marshall","family":"Hall","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[2014,3,12]]},"reference":[{"key":"S0022481200072662_ref001","first-page":"1","volume":"12","author":"Emil","year":"1947","journal-title":"Recursive unsolvability of a problem of Thue"}],"container-title":["Journal of Symbolic Logic"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0022481200072662","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,6,8]],"date-time":"2019-06-08T10:31:27Z","timestamp":1559989887000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0022481200072662\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1949,6,23]]},"references-count":1,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1949,6,23]]}},"alternative-id":["S0022481200072662"],"URL":"https:\/\/doi.org\/10.2307\/2266511","relation":{},"ISSN":["0022-4812","1943-5886"],"issn-type":[{"value":"0022-4812","type":"print"},{"value":"1943-5886","type":"electronic"}],"subject":[],"published":{"date-parts":[[1949,6,23]]}}}