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Next: Introduction

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An Overview of Head driven Bottom-up Generation

Gertjan van Noord
OTS RUU
Trans 10 Utrecht
vannoord@hutruu59.BITnet

Abstract:

In this paper I will discuss the properties of a tactical generation approach that has become popular recently: head-driven bottom-up generation.

It is assumed that bidirectional grammars written in some unification- or logic-based formalism define relations between strings and some representation, usually called logical form. The task for a generator is to generate for a given logical form the strings that are related to this logical form by the grammar.

In the paper it will be shown that the `early' approaches to this conceivement of the generation problem such as [21], [31] and [7] are not entirely satisfactory for general purposes. Furthermore I will define a simple bottom-up generator, called BUG1 for reference, as prototypical for the head-driven bottom-up approach as defended by for example [24][23][5][30]. I will argue that head-driven bottom-up generation is to be preferred because the order of processing is directed by the input logical form and the information available in lexical entries; moreover the algorithm puts fewer restrictions on grammars than some other generators.

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• Introduction
• Problems with early approaches
  • Top-down generators and left recursion
  • Shieber's chart-based generator
• Head driven bottom-up generation
  • BUG1: a head driven bottom-up generator
  • Why head driven bottom-up generation?
  • Problems and Extensions
    • Restrictions on heads
    • Nodes which share their logical form
    • Delayed evaluation of nodes
    • Verb Second
    • Other extensions
  • A uniform architecture
  • Some experimental results
• Summary
• Acknowledgements
• References
• Generation times for a DCG grammar for Dutch
• a simple DCG for Dutch
• About this document ...

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Gertjan van Noord
Fri Nov 25 13:07:08 MET 1994