We present an algorithm for simultaneously constructing both the syntax and semantics of a sentence using a Lexicalized Tree Adjoining Grammar (LTAG). This approach captures naturally and elegantly the interaction between pragmatic and syntactic constraints on descriptions in a sentence, and the inferential interactions between multiple descriptions in a sentence. At the same

The LinGO (Linguistic Grammars Online) project's English Resource Grammar and the LKB grammar development environment are language resources which are freely available for download for any purpose, including commercial use (see http://lingo.stanford.edu). Executable programs and source code are both included. In this paper, we give an outline of the LinGO English grammar and LKB system, and discuss the ways in which they are currently being used. The grammar and processing system can be used independently or combined to give a central component which can be exploited in a variety of ways. Our intention in writing this paper is to encourage more people to use the technology, which supports collaborative development on many levels.

. 1 Another important source for the interest in underspecification is lexical semantics. Example (2) is a representative for a large field of ambiguity phenomena, which are conventionally classified as lexical ambiguities, but differ from trivial cases like the homonyms bank or pen in several important ways. 1 Earlier, but less influential research on underspecification was performed in the phliqa project at Philips Research Labs, where it seems that the concept of `meta-variables' was actually discovered; see e.g. Bronnenberg et al. (1979); Landsbergen & Scha (1979); Bunt (1984; 1985). boek-pinkal.tex; 27/08/1999; 13:09; p.1 33 H. Bunt and R. Muskens (eds.) Computing Meaning. Kluwer Academic Press, Dordrecht 1999, 33--55.. 34 MANFRED PINKAL (2) John began the book Rather than locating the source of ambiguity of sentence (2) in the verb b

Abstract. In this paper, we present a unified feature-based theory of complement, adjunct, and subject extraction, in which there is no need either for valence reducing lexical rules or for phonologically null traces. Our analysis rests on the assumption that the mapping between argument structure and valence is defined by realization constraints which are satisfied by all lexical heads. Arguments can be realized as local dependents, in which case they are selected via the head’s valence features. Alternatively, arguments may be realized in a long-distance dependency construction, in which case they are selected via the head’s SLASH features. Furthermore, we argue that in English post-verbal adjuncts, as well as complements, are syntactic dependents selected by the verb, thus providing a uniform analysis of complement and adjunct extraction. Finally, we provide an alternative treatment of subject extraction which is subsumed by our general analysis and offer a new account of the that-trace effect. 1.

Abstract. In this paper we propose a compositional semantics for lexicalized tree-adjoining grammar (LTAG). Tree-local multicomponent derivations allow separation of the semantic contribution of a lexical item into one component contributing to the predicate argument structure and a second component contributing to scope semantics. Based on this idea a syntax-semantics interface is presented where the compositional semantics depends only on the derivation structure. It is shown that the derivation structure (and indirectly the locality of derivations) allows an appropriate amount of underspecification. This is illustrated by investigating underspecified representations for quantifier scope ambiguities and related phenomena such as adjunct scope and island constraints. Key words: computational semantics, lexicalized tree-adjoining grammar, quantifier scope, underspecification 1.

Dominance constraints are logical descriptions of trees that are widely used in computational linguistics. Their general satisfiability problem is known to be NP-complete. Here we identify normal dominance constraints and present an efficient graph algorithm for testing their satisfiablity in deterministic polynomial time. Previously, no polynomial time algorithm was known.

The grammar matrix is an open-source starter-kit for the development of broadcoverage HPSGs. By using a type hierarchy to represent cross-linguistic generalizations and providing compatibility with other open-source tools for grammar engineering, evaluation, parsing and generation, it facilitates not only quick start-up but also rapid growth towards the wide coverage necessary for robust natural language processing and the precision parses and semantic representations necessary for natural language understanding.

We give a detailed account of an algorithm for efficient tactical generation from underspecified logical-form semantics, using a wide-coverage grammar and a corpus of real-world target utterances. Some earlier claims about chart realization are critically reviewed and corrected in the light of a series of practical experiments. As well as a set of algorithmic refinements, we present two novel techniques: the integration of subsumption-based local ambiguity factoring, and a procedure to selectively unpack the generation forest according to a probability distribution given by a conditional, discriminative model.

We define a back-and-forth translation between Hole Semantics and dominance constraints, two formalisms used in underspecified semantics. There are fundamental differences between the two, but we show that they disappear on practically useful descriptions. Our encoding bridges a gap between two underspecification formalisms, and speeds up the processing of Hole Semantics.

We 1 present a method for automatically extracting a Stochastic Lexicalized Tree Grammar (SLTG) from an HPSG source grammar and a given corpus. Processing of a SLTG is performed by a specialized fast parser. The approach has been tested on a large English grammar and has been shown to achieve a speed-up by a factor of better than 10 compared to parsing with a highly tuned HPSG parser. Our approach is simple and transparent, and comes with no magic tuning strategies. The extracted grammars are declaratively represented and have a high degree of practical applicability. 1 Introduction Head Driven Phrase Structure Grammar (HPSG) has proven to be a quite successful formalism for specifying natural language grammars in a highly modular and compact manner [ Pollard and Sag, 1994 ] supporting the definition of complex linguistic information and interactions between information 1 Neumann was supported by a research grant from the German Federal Ministry of Education, Science, Research and...