{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T17:39:59Z","timestamp":1767893999795,"version":"3.49.0"},"reference-count":14,"publisher":"Elsevier BV","issue":"2","license":[{"start":{"date-parts":[[1982,11,1]],"date-time":"1982-11-01T00:00:00Z","timestamp":404956800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/www.elsevier.com\/tdm\/userlicense\/1.0\/"},{"start":{"date-parts":[[2013,7,17]],"date-time":"2013-07-17T00:00:00Z","timestamp":1374019200000},"content-version":"vor","delay-in-days":11216,"URL":"https:\/\/www.elsevier.com\/open-access\/userlicense\/1.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Theoretical Computer Science"],"published-print":{"date-parts":[[1982,11]]},"DOI":"10.1016\/0304-3975(89)90080-7","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T04:17:21Z","timestamp":1027657041000},"page":"119-144","source":"Crossref","is-referenced-by-count":55,"title":["The (generalized) post correspondence problem with lists consisting of two words is decidable"],"prefix":"10.1016","volume":"21","author":[{"given":"A.","family":"Ehrenfeucht","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J.","family":"Karhum\u00e4ki","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G.","family":"Rozenberg","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"78","reference":[{"key":"10.1016\/0304-3975(89)90080-7_BIB1","doi-asserted-by":"crossref","first-page":"729","DOI":"10.1137\/0209057","article-title":"Equality sets and complexity classes","volume":"9","author":"Book","year":"1980","journal-title":"SIAM J. Comput."},{"key":"10.1016\/0304-3975(89)90080-7_BIB2","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1145\/322123.322136","article-title":"A purely homomorphic characterization of recursively enumerable sets","volume":"26","author":"Culik","year":"1979","journal-title":"J. ACM"},{"key":"10.1016\/0304-3975(89)90080-7_BIB3","series-title":"Die Grenze zwischen Entscheidbarkeit und Nichtentscheidbarkeit","author":"Claus","year":"1979"},{"key":"10.1016\/0304-3975(89)90080-7_BIB4","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1051\/ita\/1980140403491","article-title":"On the equality sets for homomorphisms on free monoids with two generators","volume":"14","author":"Culik","year":"1980","journal-title":"R.A.I.R.O., Informatique Th\u00e9orique"},{"key":"10.1016\/0304-3975(89)90080-7_BIB5","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1145\/322203.322211","article-title":"Fixed point languages, equality languages and representations of recursively enumerable languages","volume":"27","author":"Engelfriet","year":"1980","journal-title":"J. ACM"},{"key":"10.1016\/0304-3975(89)90080-7_BIB6","series-title":"Parts I, II and III","article-title":"Generalized Post Correspondence Problem of length 2","author":"Ehrenfeucht","year":"1980"},{"key":"10.1016\/0304-3975(89)90080-7_BIB7","series-title":"The Mathematical Theory of Context-Free Languages","author":"Ginsburg","year":"1966"},{"key":"10.1016\/0304-3975(89)90080-7_BIB8","series-title":"Introduction to Formal Language Theory","author":"Harrison","year":"1978"},{"key":"10.1016\/0304-3975(89)90080-7_BIB9","series-title":"Introduction to Automata Theory, Languages and Computation","author":"Hopcroft","year":"1979"},{"key":"10.1016\/0304-3975(89)90080-7_BIB10","article-title":"A note on elementary homomorphisms and the regularity of equality sets","volume":"9","author":"Karhum\u00e4ki","year":"1979","journal-title":"Bull. EATCS"},{"key":"10.1016\/0304-3975(89)90080-7_BIB11","first-page":"2940","article-title":"Recursive insolubilit\u00e9 de l'equation generale de diagonalisation de deux monomorphisms de monoides libres \u03c6x = \u03a8x","volume":"257","author":"Lecerf","year":"1963","journal-title":"C.R. Acad. Sci. Paris"},{"key":"10.1016\/0304-3975(89)90080-7_BIB12","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1090\/S0002-9904-1946-08555-9","article-title":"A variant of a recursively unsolvable problem","volume":"52","author":"Post","year":"1946","journal-title":"Bull. Amer. Math. Soc."},{"key":"10.1016\/0304-3975(89)90080-7_BIB13","series-title":"Formal Languages","author":"Salomaa","year":"1973"},{"key":"10.1016\/0304-3975(89)90080-7_BIB14","first-page":"127","article-title":"Equality sets for homomorphisms on free monoids","volume":"4","author":"Salomaa","year":"1978","journal-title":"Acta Cybernet."}],"container-title":["Theoretical Computer Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.elsevier.com\/content\/article\/PII:0304397589900807?httpAccept=text\/xml","content-type":"text\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/api.elsevier.com\/content\/article\/PII:0304397589900807?httpAccept=text\/plain","content-type":"text\/plain","content-version":"vor","intended-application":"text-mining"}],"deposited":{"date-parts":[[2019,4,12]],"date-time":"2019-04-12T13:55:12Z","timestamp":1555077312000},"score":1,"resource":{"primary":{"URL":"https:\/\/linkinghub.elsevier.com\/retrieve\/pii\/0304397589900807"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1982,11]]},"references-count":14,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1982,11]]}},"alternative-id":["0304397589900807"],"URL":"https:\/\/doi.org\/10.1016\/0304-3975(89)90080-7","relation":{},"ISSN":["0304-3975"],"issn-type":[{"value":"0304-3975","type":"print"}],"subject":[],"published":{"date-parts":[[1982,11]]}}}