2,907 research outputs found
A Tractable Extension of Linear Indexed Grammars
It has been shown that Linear Indexed Grammars can be processed in polynomial
time by exploiting constraints which make possible the extensive use of
structure-sharing. This paper describes a formalism that is more powerful than
Linear Indexed Grammar, but which can also be processed in polynomial time
using similar techniques. The formalism, which we refer to as Partially Linear
PATR manipulates feature structures rather than stacks.Comment: 8 pages LaTeX, uses eaclap.sty, to appear in EACL-9
Parallel Natural Language Parsing: From Analysis to Speedup
Electrical Engineering, Mathematics and Computer Scienc
Realization of tree adjoining grammars with unification
The syntactic generator of the WIP system is based on the representation formalism "Tree Adjoining Grammars" (TAGs). We have extended the formalism by associating elementary rules of the grammar (trees) with feature structures, leading to "Tree Adjoining Grammars with Unification" (UTAGs). The extended formalism facilitates a compact and adequate representation of complex syntactic features. The contradiction between the monotonic operation of unification and the combination operation for trees - adjunction - that is nonmonotonic in a way can be solved by several approaches to realization. Two of them are presented in this work and compared with respect to the restrictions that are given by the system, i.e., the adequacy of the realization for incremental and parallel generation. It can be shown that UTAGs are subsumed by FTAGs (Feature Structure based TAGs) that have been defined by Vijay-Shanker and Joshi. That is why the results for realization can be applied to both UTAGs and a restricted version of FTAGs
Un outil pour développer et tester les grammaires d’unification polarisées
Ce mémoire présente un outil informatique pour développer et tester des grammaires d’unification polarisées, conçu entre autres pour faciliter la validation expérimentale du formalisme de la grammaire d’unification Sens-Texte (GUST) de Kahane & Lareau. Les fondements théoriques du formalisme GUP sont d’abord expliqués, puis nous décrivons la conception du module et l’évaluons avec un fragment de la grammaire GUST.This thesis presents a computer tool to develop and test polarized unification grammars that was built, namely, to help validate experimentally Kahane & Lareau’s Meaning-Text Unification Grammar (MTUG) formalism. We first describe the theory behind the PUG formalism, then we explain how the module was developed and we test it using a fragment of the MTUG grammar
Beta-Conversion, Efficiently
Type-checking in dependent type theories relies on conversion, i.e. testing given lambda-terms for equality up to beta-evaluation and alpha-renaming.
Computer tools based on the lambda-calculus currently implement conversion by means of algorithms whose complexity has not been identified, and in some cases even subject to an exponential time overhead with respect to the natural cost models (number of evaluation steps and size of input lambda-terms).
This dissertation shows that in the pure lambda-calculus it is possible to obtain conversion algorithms with bilinear time complexity when evaluation is carried following evaluation strategies that generalize Call-by-Value to the stronger case required by conversion
Approximate text generation from non-hierarchical representations in a declarative framework
This thesis is on Natural Language Generation. It describes a linguistic realisation
system that translates the semantic information encoded in a conceptual graph into an
English language sentence. The use of a non-hierarchically structured semantic representation (conceptual graphs) and an approximate matching between semantic structures allows us to investigate a more general version of the sentence generation problem
where one is not pre-committed to a choice of the syntactically prominent elements in
the initial semantics. We show clearly how the semantic structure is declaratively related to linguistically motivated syntactic representation — we use D-Tree Grammars
which stem from work on Tree-Adjoining Grammars. The declarative specification of
the mapping between semantics and syntax allows for different processing strategies
to be exploited. A number of generation strategies have been considered: a pure topdown strategy and a chart-based generation technique which allows partially successful
computations to be reused in other branches of the search space. Having a generator
with increased paraphrasing power as a consequence of using non-hierarchical input
and approximate matching raises the issue whether certain 'better' paraphrases can be
generated before others. We investigate preference-based processing in the context of
generation
Attribute value phonology
SIGLEAvailable from British Library Document Supply Centre- DSC:D93955 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
- …