We describe how multimodal grammars for dialogue systems can be written using the Grammatical Framework (GF) formalism. A proof-of-concept dialogue system constructed using these techniques is also presented. The software engineering problem of keeping grammars for different languages, modalities and systems (such as speech recognizers and parsers) in sync is reduced by the formal relationship between the abstract and concrete syntaxes, and by generating equivalent grammars from GF grammars. 1

Grammars of natural languages are needed in programs like natural language interfaces and dialogue systems, but also more generally, in software localization. Writing grammar implementations is a highly specialized task. For various reasons, no libraries have been available to ease this task. This paper shows how grammar libraries can be written in GF (Grammatical Framework), focusing on the software engineering aspects rather than the linguistic aspects. As an implementation of the approach, the GF Resource Grammar Library currently comprises ten languages. As an application, a translation system from formalized mathematics to text in three languages is outlined. 1

Abstract. The Grammatical Framework GF is a grammar formalism designed for multilingual grammars. A multilingual grammar has a shared representation, called abstract syntax, and a set of concrete syntaxes that map the abstract syntax to different languages. A GF grammar consists of modules, which can share code through inheritance, but which can also hide information to achieve division of labour between grammarians working on different modules. The goal is to make it possible for linguistically untrained programmers to write linguistically correct application grammars encoding the semantics of special domains. Such programmers can rely on resource grammars, written by linguists, which play the rôle of standard libraries. Application grammarians use resource grammars through abstract interfaces, and the type system of GF guarantees that grammaticality is preserved. The ongoing GF resource grammar project provides resource grammars for ten languages. In addition to their use as libraries, resource grammars serve as an experiment showing how much grammar code can be shared between different languages. 1.1. Multilingual grammars 1.

Creating a speech recognizer from scratch can be quite daunting for the beginner. We present a simple and economical method for creating speech recognizers. Our goal is a favorable cost/benefit ratio rather than the best possible recognition score. We are mainly interested in recognizers with restricted domains, for example for use as input to a dialog system. We have created a number of tools which make the process easier, and use a running example to illustrate how it is done. Our starting point is a Grammatical Framework grammar, and we use HTK and ATK to create the speech recognizer. 1