{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,10,22]],"date-time":"2023-10-22T14:13:29Z","timestamp":1697984009654},"reference-count":9,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2007,3,21]],"date-time":"2007-03-21T00:00:00Z","timestamp":1174435200000},"content-version":"vor","delay-in-days":6653,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Systems &amp;amp; Computers in Japan"],"published-print":{"date-parts":[[1989,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>It is shown that the class of languages generated by generalized context\u2010free grammars (gcfg's) introduced by Pollard is exactly the class of recursively enumerable sets. Next, a subclass of gcfg's called multiple context\u2010free grammars (mcfg's) is introduced and it is shown that the class of languages generated by mcfg's properly contains the class of context\u2010free languages and is properly contained in the class of context\u2010sensitive languages. In mcfg's, it is possible to account for structures involving discontinuous constituents in a particularly simple manner. Such concepts as phrase structure and derivation tree in context\u2010free grammars (cfg's) can be extended naturally in mcfg's. Furthermore, the class of languages generated by mcfg's enjoys the formal language\u2010theoretic closure properties that the class of context\u2010free languages does.<\/jats:p>","DOI":"10.1002\/scj.4690200705","type":"journal-article","created":{"date-parts":[[2007,7,7]],"date-time":"2007-07-07T18:08:56Z","timestamp":1183831736000},"page":"43-52","source":"Crossref","is-referenced-by-count":2,"title":["Generalized context\u2010free grammars and multiple context\u2010free grammars"],"prefix":"10.1002","volume":"20","author":[{"given":"Tadao","family":"Kasami","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroyuki","family":"Seki","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mamoru","family":"Fujii","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2007,3,21]]},"reference":[{"key":"e_1_2_1_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/0304-3975(79)90041-0"},{"key":"e_1_2_1_3_2","unstructured":"T.Kasami H.SekiandM.Fujii.Generalized context\u2010free grammars multiple context\u2010free grammars and head grammars. Technical Report Osaka University (1987);"},{"key":"e_1_2_1_3_3","unstructured":"WG on Natural Language of IPSJ 1987 87\u2010NL\u201063\u20101"},{"key":"e_1_2_1_4_2","unstructured":"C. J.Pollard.Generalized Phrase Structure Grammars Head Grammars and Natural Language. Ph.D. Dissertation Stanford University (Feb.1984)."},{"key":"e_1_2_1_5_2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00360802"},{"key":"e_1_2_1_6_2","volume-title":"Formal Languages","author":"Salomma A.","year":"1973"},{"key":"e_1_2_1_7_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0019-9958(74)91399-0"},{"key":"e_1_2_1_8_2","first-page":"124","article-title":"Phrase structure languages by a concurrent derivation","volume":"54","author":"Torii K.","year":"1971","journal-title":"Trans. I.E.C.E., Japan"},{"key":"e_1_2_1_9_2","first-page":"935","article-title":"On the membership problem for head languages and multiple context\u2010free languages","volume":"71","author":"Kasami T.","year":"1988","journal-title":"Trans. I.E.I.C.E., Japan"}],"container-title":["Systems and Computers in Japan"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fscj.4690200705","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/scj.4690200705","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,21]],"date-time":"2023-10-21T16:53:28Z","timestamp":1697907208000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/scj.4690200705"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1989,1]]},"references-count":9,"journal-issue":{"issue":"7","published-print":{"date-parts":[[1989,1]]}},"alternative-id":["10.1002\/scj.4690200705"],"URL":"https:\/\/doi.org\/10.1002\/scj.4690200705","archive":["Portico"],"relation":{},"ISSN":["0882-1666","1520-684X"],"issn-type":[{"value":"0882-1666","type":"print"},{"value":"1520-684X","type":"electronic"}],"subject":[],"published":{"date-parts":[[1989,1]]}}}