some computational complexity results for synchronous context free grammars
Tài liệu Báo cáo khoa học: "Efficient Parsing for Bilexical Context-Free Grammar sand Head Automaton Grammars*" pptx
... first O(n 4) results for the natural formalism of bilexical context- free grammar, and for AI- shawi's (1996) head automaton grammars. For the usual case, split head automaton grammars or ... show that the complexity is not so bad after all: • For bilexicalized context- free grammars, O(n 4) is possible. • The O(n 4) result also holds for head au- tomaton grammars. • For a very common ... assemble such subderivations into a full parse. 2 Notation for context- free grammars The reader is assumed to be familiar with context- free grammars. Our notation fol- 1Other relevant parsers simultaneously...
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Báo cáo khoa học: "Optimal rank reduction for Linear Context-Free Rewriting Systems with Fan-Out Two" pot
... Association for Computational Linguistics, pages 525–533,Uppsala, Sweden, 11-16 July 2010.c2010 Association for Computational LinguisticsOptimal rank reduction for Linear Context- Free Rewriting ... reduc-tion of a context- free grammar production intoChomsky normal form. However, in the LCFRScase some productions might not be reducible tor = 2, and the process stops at some larger value for r, ... IntroductionLinear Context- Free Rewriting Systems(LCFRSs) have been introduced by Vijay-Shanker et al. (1987) for modeling the syntaxof natural language. The formalism extends thegenerative capacity of context- free...
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Báo cáo khoa học: "Issues Concerning Decoding with Synchronous Context-free Grammar" docx
... losing the richer information offeredby GHKM grammar.6 ConclusionIn this paper, we discussed several issues concerningdecoding with synchronous context- free grammars, focusing on grammars resulting ... outrules with useful contextual information. In addi-tion, scope-filtering does not accommodate early lan-guage model state integration. We compare the twowith an experiment. For the rest of the ... adding aheuristic to push up the cost of virtual items for faircomparison. For our experiments, we use an outside estimateas a heuristic for a virtual item. Consider the follow-ing rule binarization...
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Báo cáo khoa học: "Lexicalized Context-Free Grammars" pot
... extensions of context- free grammars. To appear in Mathematical Sys- tems Theory. Vijay-Shanker, K. and [)avid Weir. 1993b. Pars- ing some constrained grammar formalisms. To appear in Computational ... 1]) fori=0 ton-l for all node 71 in A U I labeled by ai+l call Add0/, t, i, i + 1) ;; induction (G'[i, i + k] = (;[i, j] + (:[j, i + k]) for k = 2 to n for i = 0 to n- k forj=i+ ... contains a node for every symbol in E U NT and an arc for every rule in P as follows. For each terminal and non-terminal symbol X in G create a node in LCG labeled with X. For each rule X...
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Báo cáo khoa học: "PARALLEL MULTIPLE CONTEXT-FREE GRAMMARS, FINITE-STATE TRANSLATION SYSTEMS, AND POLYNOMIAL-TIME RECOGNIZABLE SUBCLASSES OF LEXICAL-FUNCTIONAL GRAMMARS" docx
... clarify the gen- erative capacities of such grammars and devices. Parallel multiple context- free grammars (pm- cfg's) and multiple context- free grammars (mcfg's) were introduced in ... "Generalized Context- Free Grammars and Multiple Context- Free Grammars& quot;, Trans. IEICE, J71-D-I, 5:758-765. Kasami, T. et al. 1988b. "On the Membership Prob- lem for Head Language ... "Generalized Phrase Structure Grammars, Head Grammars and Natural Language", Ph.D. dissertation, Stanford University. Rounds, W.C. 1969. " ;Context- Free Grammars on Trees", Proc....
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Báo cáo khoa học: "A Tree Transducer Model for Synchronous Tree-Adjoining Grammars" pdf
... 1067–1076,Uppsala, Sweden, 11-16 July 2010.c2010 Association for Computational LinguisticsA Tree Transducer Model for Synchronous Tree-Adjoining Grammars Andreas MalettiUniversitat Rovira i VirgiliAvinguda ... as synchronous tree substitution gram-mars (STSG). We refer to Chiang (2006) for anintroduction to synchronous devices.Let us recall the formal definition. An ex-tended tree transducer (for ... (2009) for a moredetailed exposition to XTT.5 Synchronous tree-adjoining grammarXTT are a simple, natural model for tree trans-formations, however they are not suitably ex-pressive for all...
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Báo cáo khoa học: "Parsing Non-Recursive Context-Free Grammars" doc
... Italysatta@dei.unipd.itAbstractWe consider the problem of parsingnon-recursive context- free grammars, i.e., context- free grammars that generate finitelanguages. In natural language process-ing, this ... consists of symbols of the form for , and contains the followingtransitions: For each pair of rules and ,contains:and. For each rule , contains:.Observe that for all PDAs constructed as ... ma-chine translation. We present two tabu-lar algorithms for parsing of non-recursive context- freegrammars, and show that theyperform well in practical settings, despitethe fact that this...
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Báo cáo khoa học: "PRECISE N-GRAM PROBABILITIES FROM STOCHASTIC CONTEXT-FREE GRAMMARS" pptx
... berkeley, edu Abstract We present an algorithm for computing n-gram probabil- ities from stochastic context- free grammars, a procedure that can alleviate some of the standard problems associated ... generalizes straightforwardly to the more general Canonical Two-Form (Graham et al., 1980) format, and in the case of bigrams (n =- 2) it can even be modified to work directly for arbitrary SCFGs. ... 1 for a SCFG G, we immediately have an n-gram grammar for the language generated by G. Computing expectations Our goal now is to compute the substring expectations for a given grammar. Formalisms...
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Báo cáo khoa học: "ON THE SUCCINCTNESS PROPERTIES OF UNORDERED CONTEXT-FREE GRAMMARS" ppt
... ID/LP grammars. The results have im- plications for the description of free word order languages. 2 Introduction Context free grammars in immediate dominance and linear precedence format ... unordered, or ID/LP grammars, are e.xponentially more succinct than context- free grammars, by exhibiting a sequence (L,~) of finite languages such that the size of any CFG for L,~ must grow ... increasing context- free de- scriptions. ~Ve have the following theorem. Theorem 2 Consider the set Mn(n=) of all length n 2 strings of Mn. Then there is a constant c > 1 such that any context. free...
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Báo cáo khoa học: "Authorship Attribution Using Probabilistic Context-Free Grammars" doc
... approach for authorship attribution, the task of iden-tifying the author of a document, usingprobabilistic context- free grammars. Ourapproach involves building a probabilistic context- free grammar ... (discussedbelow). However, for some datasets, even thisimprovement was not sufficient to outperform thebest baseline.The results for PCFG and PCFG-I demon-strate that syntactic information alone is ... model outper-forms the baseline for the Football dataset, PCFG-E outperforms the best baseline for the Poetryand Business datasets. For the Cricket and Traveldatasets, the performance of the...
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- tài liệu về context free grammars
- synchronous context free grammars
- evaluating syntactic complexity features for automated scoring
- on the computational complexity
- 202 useful exercises for ielts audio free download
- vocabulary for toefl ibt free
- vocabulary for toefl ibt free download
- binarization of synchronous context free grammars
- a probabilistic context free grammar for melodic reduction
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