Integrating a unification-based semantics in a large scale Lexicalised Tree Adjoining Grammar for French

International audienceIn contrast to LFG and HPSG, there is to date no large scale Tree Adjoining Grammar (TAG) equiped with a compositional semantics. In this paper, we report on the integration of a unification-based semantics into a Feature-Based Lexicalised TAG for French consisting of around 6 000 trees. We focus on verb semantics and show how factorisation can be used to support a compact and principled encoding of the semantic information that needs to be associated with each of the verbal elementary trees. The factorisation is made possible by the use of \xmg , a high-level linguistic formalism designed to specify and compile computational grammars and in particular, grammars based on non-local trees or tree descriptions

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

XMG : eXtensible MetaGrammar

International audienceIn this article, we introduce eXtensible MetaGrammar (xmg), a framework for specifying tree-based grammars such as Feature-Based Lexicalised Tree-Adjoining Grammars (FB-LTAG) and Interaction Grammars (IG). We argue that xmg displays three features which facilitate both grammar writing and a fast prototyping of tree-based grammars. Firstly, \xmg\ is fully declarative. For instance, it permits a declarative treatment of diathesis that markedly departs from the procedural lexical rules often used to specify tree-based grammars. Secondly, the \xmg\ language has a high notational expressivity in that it supports multiple linguistic dimensions, inheritance and a sophisticated treatment of identifiers. Thirdly, xmg is extensible in that its computational architecture facilitates the extension to other linguistic formalisms. We explain how this architecture naturally supports the design of three linguistic formalisms namely, FB-LTAG, IG, and Multi-Component Tree-Adjoining Grammar (MC-TAG). We further show how it permits a straightforward integration of additional mechanisms such as linguistic and formal principles. To further illustrate the declarativity, notational expressivity and extensibility of \xmg , we describe the methodology used to specify an FB-LTAG for French augmented with a unification-based compositional semantics. This illustrates both how xmg facilitates the modelling of the tree fragment hierarchies required to specify tree-based grammars and of a syntax/semantics interface between semantic representations and syntactic trees. Finally, we briefly report on several grammars for French, English and German that were implemented using \xmg\ and compare \xmg\ to other existing grammar specification frameworks for tree-based grammars

SemTAG: a platform for specifying Tree Adjoining Grammars and performing TAG-based Semantic Construction

Demo Session. Available at http://aclweb.org/anthology-new/P/P07/P07-2004.pdfInternational audienceIn this paper, we introduce SemTAG , a free and open software architecture for the development of Tree Adjoining Grammars integrating a compositional semantics. SemTAG differs from XTAG in two main ways. First, it provides an expressive grammar formalism and compiler for factorising and specifying TAGs. Second, it supports semantic construction

A Hybrid Approach To Generating from the KBGen Knowledge-Base

International audienceThis abstract describes a contribution to the 2013 KBGen Challenge from CNRS/LORIA and the University of Lorraine. Our contribution focuses on an attempt to automate the extraction of a Feature Based Tree Adjoining Grammar equipped with a unification based compositional semantics which can be used to generate from KBGen data

Representation of Linguistic and Domain Knowledge for Second Language Learning in Virtual Worlds

International audienceThere has been much debate, both theoretical and practical, on how to link ontologies and lexicons in natural language processing (NLP) applications. In this paper, we focus on an application in which lexicon and ontology are used to generate teaching material. We briefly describe the application (a serious game for language learning). We then zoom in on the representation and interlinking of the lexicon and of the ontology. We show how the use of existing standards and of good practice principles facilitates the design of our resources while satisfying the expressivity requirements set by natural language generation

Quelo Natural Language Interface: Generating queries and answer descriptions

International audienceWe present an intelligent NLI interface, namely Quelo NLI, for querying and exploring semantic data. Its intelligence lies in the use of reasoning services over an ontology. These support the intentional navigation of the underlying datasource and the formulation of queries that are consistent with respect to it. Its Natural Language Generation (NLG) module masks the formulation of queries as the composition of English text and generates descriptions of query answers. An important feature of Quelo NLI is that it is portable as it is not bound to an ontology of a specific domain. We describe Quelo NLI functionality and present a grammar-based natural language generation approach that better supports thedomain-independent generation of fluent queries and naturally extends for the generation of answers descriptions. We concentrate on describing the generation resources, namely a domain-independent hand-written grammar and a lexicon that is automatically extracted from concepts and relations of the underlying ontology

Multiple Adjunction in Feature-based Tree-adjoining Grammar

International audienceIn parsing with Tree Adjoining Grammar (TAG), independent derivations have been shown by Schabes and Shieber (1994) to be essential for correctly supporting syntactic analysis, semantic interpretation, and statistical language modeling. However, the parsing algorithm they propose is not directly applicable to Feature-Based TAGs (FB-TAG). We provide a recognition algorithm for FB-TAG that supports both dependent and independent derivations. The resulting algorithm combines the benefits of independent derivations with those of Feature-Based grammars. In particular , we show that it accounts for a range of interactions between dependent vs. independent derivation on the one hand, and syntactic constraints, linear ordering, and scopal vs. nonscopal semantic dependencies on the other hand