{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2022,4,5]],"date-time":"2022-04-05T13:32:27Z","timestamp":1649165547377},"reference-count":10,"publisher":"World Scientific Pub Co Pte Lt","issue":"04","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Found. Comput. Sci."],"published-print":{"date-parts":[[2008,8]]},"abstract":"<jats:p> We define a complexity measure on context-free grammars called end. Roughly speaking, for a context-free grammar G, end<jats:sub>G<\/jats:sub>(n) measures the distance of variables from the ends of sentential forms along the derivations of words in L(G) of length n. We prove in a constructive way the regularity of L(G)wheneverend<jats:sub>G<\/jats:sub>(n)is constant. Yet, we improve on this by showing that ifL(G)is nonregular thenend<jats:sub>G<\/jats:sub>(n) = \u03a9<jats:sub>\u221e<\/jats:sub>( log n). We establish the optimality of such bound. Finally, we show that, in case of unambiguous context-free grammars, the end lower bound for generating nonregular languages turns out to be linear. <\/jats:p>","DOI":"10.1142\/s0129054108005991","type":"journal-article","created":{"date-parts":[[2008,8,6]],"date-time":"2008-08-06T10:30:40Z","timestamp":1218018640000},"page":"845-857","source":"Crossref","is-referenced-by-count":0,"title":["A REGULARITY CONDITION FOR CONTEXT-FREE GRAMMARS"],"prefix":"10.1142","volume":"19","author":[{"given":"BEATRICE","family":"PALANO","sequence":"first","affiliation":[{"name":"Dipartimento di Scienze dell'Informazione, Universit\u00e0 degli Studi di Milano, Via Comelico 39\/41, 20135 Milano, Italy"}]}],"member":"219","published-online":{"date-parts":[[2011,11,20]]},"reference":[{"key":"rf1","doi-asserted-by":"publisher","DOI":"10.1007\/s00236-003-0133-8"},{"key":"rf3","first-page":"143","volume":"14","author":"Bar-Hillel Y.","journal-title":"Z. Phonetik Sprachwiss. Kommunikationsforsch."},{"key":"rf4","doi-asserted-by":"publisher","DOI":"10.1016\/S0019-9958(67)90771-1"},{"key":"rf5","doi-asserted-by":"publisher","DOI":"10.1016\/S0019-9958(59)90362-6"},{"key":"rf6","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-642-74932-2"},{"key":"rf8","doi-asserted-by":"publisher","DOI":"10.1016\/S0019-9958(71)90095-7"},{"key":"rf9","volume-title":"Formal languages and their relation to automata","author":"Hopcroft J.","year":"1969"},{"key":"rf11","doi-asserted-by":"publisher","DOI":"10.1145\/321356.321364"},{"key":"rf12","doi-asserted-by":"publisher","DOI":"10.1016\/S0019-9958(69)90164-8"},{"key":"rf13","doi-asserted-by":"publisher","DOI":"10.1007\/3-540-58355-6"}],"container-title":["International Journal of Foundations of Computer Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.worldscientific.com\/doi\/pdf\/10.1142\/S0129054108005991","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,8,7]],"date-time":"2019-08-07T15:23:50Z","timestamp":1565191430000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.worldscientific.com\/doi\/abs\/10.1142\/S0129054108005991"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2008,8]]},"references-count":10,"journal-issue":{"issue":"04","published-online":{"date-parts":[[2011,11,20]]},"published-print":{"date-parts":[[2008,8]]}},"alternative-id":["10.1142\/S0129054108005991"],"URL":"https:\/\/doi.org\/10.1142\/s0129054108005991","relation":{},"ISSN":["0129-0541","1793-6373"],"issn-type":[{"value":"0129-0541","type":"print"},{"value":"1793-6373","type":"electronic"}],"subject":[],"published":{"date-parts":[[2008,8]]}}}