Grammatical Framework (GF) is a special-purpose functional language for defining grammars. It uses a Logical Framework (LF) for a description of abstract syntax, and adds to this a notation for defining concrete syntax. GF grammars themselves are purely declarative, but can be used both for linearizing syntax trees and parsing strings. GF can describe both formal and natural languages. The key notion of this description is a grammatical object, which is not just a string, but a record that contains all information on inflection and inherent grammatical features such as number and gender in natural languages, or precedence in formal languages. Grammatical objects have a type system, which helps to eliminate run-time errors in language processing. In the same way as an LF, GF uses...

We describe an implemented spoken-language dialogue system for a travel-planning domain, which accesses a commercially available travelinformation web-server and supports a flexible mixed-initiative dialogue strategy. We argue, based on data from initial Wizard-of-Oz experiments, that mixed-initiative strategies are appropriate for many types of user, but require more sophisticated architectures for processing of language and dialogue; we then use these observations to motivate an architecture which combines parallel deep and shallow natural language analysis engines and an agenda-driven dialogue manager. We outline the top-level processing strategy used by the dialogue manager, and also a novel formalism, which we call Flat Utterance Description, that allows us to reduce the output of the deep and shallow languageprocessing engines to a common representation.

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This paper shows how a dialogue system for information-seeking dialogues can be implemented in a type-theory-based syntax editor, originally developed for editing mathematical proofs. The implementation gives a simple logical metatheory to such dialogue systems and also suggests new functions to them, e.g. a local undo operation. The method developed provides a logically based declarative way of implementing simple dialogue systems that is easy to port to new domains.