tailieunhanh - Báo cáo khoa học: "Efficient Parsing for Bilexical Context-Free Grammar sand Head Automaton Grammars*"

Several recent stochastic parsers use bilexical grammars, where each word type idiosyncratically prefers particular complements with particular head words. We present O(n 4) parsing algorithms for two bilexical formalisms, improving the prior upper bounds of O(n5). For a common special case that was known to allow O(n 3) parsing (Eisner, 1997), we present an O(n 3) algorithm with an improved grammar constant. | Efficient Parsing for Bilexical Context-Free Grammars and Head Automaton Grammars Jason Eisner Giorgio Satta Dept of Computer Information Science Dip. di Elettronica e Informatica University of Pennsylvania Università di Padova 200 South 33rd Street via Gradenigo 6 A Philadelphia PA 19104 USA 35131 Padova Italy jeisner@ satta@ Abstract Several recent stochastic parsers use bilexical grammars where each word type idiosyncrat-ically prefers particular complements with particular head words. We present O n4 parsing algorithms for two bilexical formalisms improving the prior upper bounds of O n5 . For a common special case that was known to allow O n3 parsing Eisner 1997 we present an ơ n3 algorithm with an improved grammar constant. 1 Introduction Lexicalized grammar formalisms are of both theoretical and practical interest to the computational linguistics community. Such formalisms specify syntactic facts about each word of the language in particular the type of arguments that the word can or must take. Early mechanisms of this sort included categorial grammar Bar-Hillel 1953 and subcategorization frames Chomsky 1965 . Other lexi-calized formalisms include Schabes et al. 1988 Mel cuk 1988 Pollard and Sag 1994 . Besides the possible arguments of a word a natural-language grammar does well to specify possible head words for those arguments. Convene requires an NP object but some NPs are more semantically or lexically appropriate here than others and the appropriateness depends largely on the NP s head . meeting . We use the general term bilexical for a grammar that records such facts. A bilexical grammar makes many stipulations about the compatibility of particular pairs of words in particular roles. The acceptability of Nora convened the The authors were supported respectively under ARPA Grant N6600194-C-6043 Human Language Technology and Ministero dell Universita e della Ricerca Scientifica e Tecnologica project Methodologies and .

TÀI LIỆU MỚI ĐĂNG
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.