[PDF] Top 20 Efficient parsing with Linear Context Free Rewriting Systems

... Discontinuity in constituent structures (cf. figure 1 & 2) is important for a variety of reasons. For one, it allows a tight correspondence between syntax and semantics by letting constituent struc- ture express ... See full document

... these systems lack Chomsky-like normal forms for fixed fan-out (Rambow and Satta, 1999) that are es- pecially convenient in tabular ...mildly context-sensitive formalisms, and TAG in particular: TAGs can be ... See full document

... for parsing LCFRSs build a dynamic programming chart of recognized nonter- minals bottom-up, in a manner analogous to the CKY algorithm for CFGs (Hopcroft and Ullman, 1979), but with time and space complexity that ... See full document

... a Linear Context-Free Rewrit- ing System (LCFRS) into two simpler produc- tions by factoring out a subset of the nontermi- nals on the production’s righthand ...the parsing complexity of the ... See full document

... The class of output languages of deterministic tree-walking transducers is known to be equal to the class of yields of images of the regular tree languages under finite-copying top-down [r] ... See full document

... equivalence means that the derivations of the orig- inal grammar can be reconstructed using some sim- ple homomorphism (c.f. Nijholt, 1980). Our contri- bution is significant because the existing algorithms for ... See full document

... the parsing complexity that comes with allowing discontinuities, this is a promising finding since it has already been shown for monolingual parsing that restricting the fan-out to 2 drastically reduces ... See full document

... Seki et al. (1991, Thm 3.9(3), pg. 203) have shown that the class of languages generated by LCFRSs are closed under intersection with regular lan- guages. 1 The proof is a generalization of the proof that ... See full document

... The rewriting head non-deterministically picks an instance number for a round of rewriting (single rule application) from a pool sufficiently large to differentiate between the maximal number of non- ... See full document

... casting context-free gram- mars into binary ...the context- free case, for LCFRS there are worst case gram- mars in which rank reduction is not possible at all, as shown in (Rambow and Satta, ... See full document

... data-driven parsing with Linear Context-Free Rewriting System (LCFRS), markovized gram- mars are obtained through the annotation of bi- narization non-terminals during grammar bina- ... See full document

... formal systems for modeling the syntax of nat- ural ...in rewriting systems that enlarge the generat- ive power of context-free grammars, still remain- ing far below the power of the ... See full document

... syntactic parsing has become a necessary research area as statisti- cal grammars grow in accuracy and size and as more NLP applications leverage syntac- tic ...log linear model, we learn the optimal ... See full document

... wise. We train a log linear model with the averaged perceptron algorithm (Collins, 2002) using unigram word and POS-tag 2 features from a five word win- dow. We also trained models with bi-gram and tri- gram ... See full document

... nizing context-free grammars recently proposed by Melamed ...synchronous rewriting is implemented by means of an indexing relation that is maintained over occurrences of nonterminals in a sentential ... See full document

... Abstract Recent results have established that there is a family of languages that is exactly the class of languages generated by three independently developed grammar formalisms: Tree Ad[r] ... See full document

... that Context-Free Grammar (CFG) does not provide enough expressivity to de- scribe natural ...CFG parsing, some of the information present in constituency treebanks, namely the annotation of ... See full document

... The intuition behind matrices of the type of T (meaning T and, as we see later, products of T with itself, or its transitive closure) is that each cell indexed by (i, j) in such a matrix consists of all nonterminals that ... See full document

... A problem of the previous estimate is that with a large number of non-terminals the computation of the estimate requires too much space. Our ex- periments have shown that for treebank parsing where we have, after ... See full document

... Most constituency treebanks rely on an annotation backbone based on Context-Free Grammar (CFG). Discontinuities cannot be modeled with CFG, because they require a larger domain of locality than the one ... See full document