799 research outputs found
On the Membership Problem for Non-Linear Abstract Categorial Grammars
International audienceIn this paper we show that the membership problem for second order non- linear Abstract Categorial Grammars is decidable. A consequence of that result is that Montague-like semantics yield to a decidable text generation problem. Furthermore the proof we propose is based on a new tool, Higher Order Intersection Signatures, which grasps statically dynamic properties of λ-terms and presents an interest in its own
Automatic F-Structure Annotation from the AP Treebank
We present a method for automatically annotating treebank resources with functional structures. The method defines systematic patterns of correspondence between partial PS configurations and functional structures. These are applied to PS rules extracted from treebanks. The set of techniques which we have developed constitute a methodology for corpus-guided grammar development. Despite the widespread belief that treebank representations are not very useful in grammar development, we show that systematic patterns of c-structure to f-structure correspondence can be simply and successfully stated over such rules. The method is partial in that it requires manual correction of the annotated grammar rules
A Generalised Quantifier Theory of Natural Language in Categorical Compositional Distributional Semantics with Bialgebras
Categorical compositional distributional semantics is a model of natural
language; it combines the statistical vector space models of words with the
compositional models of grammar. We formalise in this model the generalised
quantifier theory of natural language, due to Barwise and Cooper. The
underlying setting is a compact closed category with bialgebras. We start from
a generative grammar formalisation and develop an abstract categorical
compositional semantics for it, then instantiate the abstract setting to sets
and relations and to finite dimensional vector spaces and linear maps. We prove
the equivalence of the relational instantiation to the truth theoretic
semantics of generalised quantifiers. The vector space instantiation formalises
the statistical usages of words and enables us to, for the first time, reason
about quantified phrases and sentences compositionally in distributional
semantics
On the Complexity of Free Word Orders
International audienceWe propose some extensions of mildly context-sensitive for- malisms whose aim is to model free word orders in natural languages. We give a detailed analysis of the complexity of the formalisms we propose
Type-theoretic extensions of Abstract Categorial Grammars
Abstract Categorial Grammars (ACG), in their original definition, are based on the linear λ-calculus. This choice derives from the traditional categorial grammars, which are based on resource sensitive logics. From a language-theoretic standpoint, this linearity constraint does not result in a weak expressive power of the formalism. For instance, the string languages generated by the second-order ACGs (whose parsing is known to be polynomial) corresponds to the class of mildly context sensitive lan- guages. From a more practical point of view, however, it would be interesting to increase the intentional expressive power of the formalism by providing high level constructs. For instance, one would like to provide the ACGs with feature structures, as it is the case in most current grammatical formalisms. In previous paper, a possible way of extending the ACGs is suggested. It consists of enriching the type system of the formalism with new type constructors. The present paper elaborates on this proposal
Lexicalized non-local MCTAG with dominance links is NP-complete
An NP-hardness proof for non-local Multicomponent Tree Adjoining Grammar
(MCTAG) by Rambow and Satta (1st International Workshop on Tree
Adjoining Grammers 1992), based on Dahlhaus and Warmuth (in J Comput
Syst Sci 33:456–472, 1986), is extended to some linguistically
relevant restrictions of that formalism. It is found that there are
NP-hard grammars among non-local MCTAGs even if any or all of the
following restrictions are imposed: (i) lexicalization: every tree in
the grammar contains a terminal; (ii) dominance links: every tree set
contains at most two trees, and in every such tree set, there is a link
between the foot node of one tree and the root node of the other tree,
indicating that the former node must dominate the latter in the derived
tree. This is the version of MCTAG proposed in Becker et al.
(Proceedings of the 5th conference of the European chapter of the
Association for Computational Linguistics 1991) to account for German
long-distance scrambling. This result restricts the field of possible
candidates for an extension of Tree Adjoining Grammar that would be both
mildly context-sensitive and linguistically adequate
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