1,638 research outputs found
An Alternative Conception of Tree-Adjoining Derivation
The precise formulation of derivation for tree-adjoining grammars has
important ramifications for a wide variety of uses of the formalism, from
syntactic analysis to semantic interpretation and statistical language
modeling. We argue that the definition of tree-adjoining derivation must be
reformulated in order to manifest the proper linguistic dependencies in
derivations. The particular proposal is both precisely characterizable through
a definition of TAG derivations as equivalence classes of ordered derivation
trees, and computationally operational, by virtue of a compilation to linear
indexed grammars together with an efficient algorithm for recognition and
parsing according to the compiled grammar.Comment: 33 page
Edge-Based Best-First Chart Parsing
Best-first probabilistic chart parsing attempts to parse efficiently by working on edges that are judged 'best' by some probabilistic figure of merit (FOM). Recent work has used proba- bilistic context-free grammars (PCFGs) to sign probabilities to constituents, and to use these probabilities as the starting point for the FOM. This paper extends this approach to us- ing a probabilistic FOM to judge edges (incomplete constituents), thereby giving a much finergrained control over parsing effort. We show how this can be accomplished in a particularly simple way using the common idea of binarizing the PCFG. The results obtained are about a factor of twenty improvement over the best prior results -- that is, our parser achieves equivalent results using one twentieth the number of edges. Furthermore we show that this improvement is obtained with parsing precision and recall levels superior to those achieved by exhaustive parsing
Statistical Function Tagging and Grammatical Relations of Myanmar Sentences
This paper describes a context free grammar (CFG) based grammatical relations
for Myanmar sentences which combine corpus-based function tagging system. Part
of the challenge of statistical function tagging for Myanmar sentences comes
from the fact that Myanmar has free-phrase-order and a complex morphological
system. Function tagging is a pre-processing step to show grammatical relations
of Myanmar sentences. In the task of function tagging, which tags the function
of Myanmar sentences with correct segmentation, POS (part-of-speech) tagging
and chunking information, we use Naive Bayesian theory to disambiguate the
possible function tags of a word. We apply context free grammar (CFG) to find
out the grammatical relations of the function tags. We also create a functional
annotated tagged corpus for Myanmar and propose the grammar rules for Myanmar
sentences. Experiments show that our analysis achieves a good result with
simple sentences and complex sentences.Comment: 16 pages, 7 figures, 8 tables, AIAA-2011 (India). arXiv admin note:
text overlap with arXiv:0912.1820 by other author
Practical experiments with regular approximation of context-free languages
Several methods are discussed that construct a finite automaton given a
context-free grammar, including both methods that lead to subsets and those
that lead to supersets of the original context-free language. Some of these
methods of regular approximation are new, and some others are presented here in
a more refined form with respect to existing literature. Practical experiments
with the different methods of regular approximation are performed for
spoken-language input: hypotheses from a speech recognizer are filtered through
a finite automaton.Comment: 28 pages. To appear in Computational Linguistics 26(1), March 200
Enhancing practical TAG parsing efficiency by capturing redundancy
International audienceParsing efficiency within the context of tree adjoining grammars (TAGs) depends not only on the size of the input sentence but also, linearly, on the size of the input TAG, which can attain several thousands of elementary trees. We propose a factorized, finite-state TAG representation which copes with this combinatorial explosion. The associated parsing algorithm substantially increases the parsing performance on a real-size French TAG grammar
Principles and Implementation of Deductive Parsing
We present a system for generating parsers based directly on the metaphor of
parsing as deduction. Parsing algorithms can be represented directly as
deduction systems, and a single deduction engine can interpret such deduction
systems so as to implement the corresponding parser. The method generalizes
easily to parsers for augmented phrase structure formalisms, such as
definite-clause grammars and other logic grammar formalisms, and has been used
for rapid prototyping of parsing algorithms for a variety of formalisms
including variants of tree-adjoining grammars, categorial grammars, and
lexicalized context-free grammars.Comment: 69 pages, includes full Prolog cod
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