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.

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.

One major obstacle to efficient processing of large wide coverage grammars in unification-based grammatical frameworks such as HPSG is the time and space cost of the unification operation itself. In a grammar development system it is not appropriate to address this problem with techniques which involve lengthy compilation, since this slows down the edit-test-debug cycle. Nor is it possible to radically restructure the grammar. In this paper we describe novel extensions to an existing efficient unification algorithm which improve its space and time behaviour (without affecting its correctness) by substantially increasing the amount of structure sharing that takes place. We also describe a fast and automatically tunable pre-unification filter (the "quick check") which in practice detects a large proportion of unifications that if performed would fail. Finally, we present an efficient algorithm for checking for subsumption relationships between two feature structures; a special case of this gives a fast equality test. The subsumption check is used in a parser (described elsewhere in this volume) which "packs" local ambiguities to avoid performing redundant sub-computations.

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...

Abstract. In this paper I discuss several possible analyses for constituent order in German. Approaches that assume continuous constituents are compared with an approach that assumes discontinuous constituents. I will show that certain proposals that have been made to analyze constituent order are either not adequate or cannot be implemented with currently available systems. For the proposals that can be implemented I will discuss the amount of work a parser has to do. I then compare two implementations of larger fragments of German: the Verbmobil grammar and the Babel grammar. It is shown that the amount of work to be done to parse the Verbmobil grammar is significantly higher than the work that has to be done parsing with the Babel grammar. Key words: German, HPSG, implementation, linearization, parsing 1.

Abstract. In this paper, I propose an implementation of relative clause extraposition in German. The proposal builds on Kiss (in press) who treats relative clause extraposition as an anaphoric process by means of percolation of anchors to which the relative clause is bound. I discuss several sources of spurious ambiguity in Kiss’s original formulation and suggest a two-step percolation of anchors that crucially distinguishes right-peripheral from central or left-peripheral percolation. Since extraposition is fairly productive, and phrase-structure alternates between head initial (prepositional phrases, V-initial) and head-final structures (postpositional phrases, V-final), German provides a good testing ground for techniques controlling spurious ambiguity that may easily be ported to languages where phrase structure is more canonical and/or extraposition more restricted. Finally, the performance of the Kissstyle approach is compared to an alternative implementation in terms of rightward movement, similar to Keller (1995).

Over the past few years significant progress was accomplished in efficient processing with wide-coverage hpsg grammars. hpsg-based parsing systems are now available that can process medium-complexity sentences (of ten to twenty words, say) in average parse times equivalent to real (i.e. human reading) time. A large number of engineering improvements in current hpsg systems were achieved through collaboration of multiple research centers and mutual exchange of experience, encoding techniques, algorithms, and even pieces of software. This article presents an approach to grammar and system engineering, termed competence & performance profiling, that makes systematic experimentation and the precise empirical study of system properties a focal point in development. Adapting the profiling metaphor familiar from software engineering to constraint-based grammars and parsers, enables developers to maintain an accurate record of system evolution, identify grammar and system deficiencies quickl...

3.24> 871 71 90.9 6.48 58.7 23.32 Phenomenon 2.08 total items # (generated by [incr tsdb(1)] at 14-nov-98 (17:58) (c) oe@coli.uni-sb.de) gctime gc time first reading first reading all readings all readings total cpu time total cpu time Parsing Time Parsing Time String Length (`i-length') String Length (`i-length') 2 2 4 6 6 8 8 10 10 12 12 14 14 0 0 5 5 10 10 15 15 [ incr tsdb ()] Competence and Performance Laboratory User & Reference Manual Stephan Oepen Computational Linguistics --- Saarland University preface --- i Preface [...] we view the discovery of parsing strategies as a largely experimental process of incremental optimization. [Erbach (1991)] [...] the study and optimi

We present an overview of a comprehensive formal theory of the interpretation of sentential fragments, which has as components an empirically validated taxonomy, an analysis of the syntax and compositional semantics of fragments, and a formalisation of their contextual interpretation. We also briefly describe an implementation of this theory, and quantify the potential practical use of handling fragments in dialogue systems.

Based on a detailed case study of parallel grammar development distributed across two sites, we review some of the requirements for regression testing in grammar engineering, summarize our approach to systematic competence and performance profiling, and discuss our experience with grammar development for a commercial application.