From RAGS to RICHES: Exploiting the Potential of a Flexible Generation Architecture

From RAGS to RICHES: exploiting the potential of a flexible generation architecture � Lynne Cahill � , John Carroll � , Roger Evans � , Daniel Paiva � , Richard Power � , Donia Scott � and Kees van Deemter � � ITRI, University of Brighton Brighton, BN2 4GJ, UK Firstname.Lastname@itri.bton.ac.uk � School of Cognitive and Computing Sciences, University of Sussex Brighton, BN1 9QH, UK johnca@cogs.susx.ac.uk Abstract The RAGS proposals for generic speci- fication of NLG systems includes a de- tailed account of data representation, but only an outline view of processing aspects. In this paper we introduce a modular processing architecture with a concrete implementation which aims to meet the RAGS goals of transparency and reusability. We illustrate the model with the RICHES system – a generation system built from simple linguistically- motivated modules. 1 Introduction As part of the RAGS (Reference Architecture for Generation Systems) project, Mellish et al (2000) introduces a framework for the representation of data in NLG systems, the RAGS ‘data model’. This model offers a formally well-defined declar- ative representation language, which supports the complex and dynamic data requirements of gen- eration systems, e.g. different levels of repre- sentation (conceptual to syntax), mixed represen- tations that cut across levels, partial and shared structures and ‘canned’ representations. However � We would like to acknowledge the financial support of the EPSRC (RAGS – Reference Architecture for Generation Systems: grant GR/L77102 to Donia Scott), as well as the intellectual contribution of our partners at Edinburgh (Chris Mellish and Mike Reape: grant GR/L77041 to Mellish) and other colleagues at the ITRI, especially Nedjet Bouayad- Agha. We would also like to acknowledge the contribution of colleagues who worked on the RICHES system previ- ously: Neil Tipper and Rodger Kibble. We are grateful to our anonymous referees for their helpful comments. RAGS, as described in that paper, says very little about the functional structure of an NLG system, or the issues arising from more complex process- ing regimes (see for example Robin (1994), Inuie et al., (1992) for further discussion). NLG systems, especially end-to-end, applied NLG systems, have many functionalities in com- mon. Reiter (1994) proposed an analysis of such systems in terms of a simple three stage pipeline. More recently Cahill et al (1999) attempted to re- peat the analysis, but found that while most sys- tems did implement a pipeline, they did not im- plement the same pipeline – different functional- ities occurred in different ways and different or- ders in different systems. But this survey did identify a number of core functionalities which seem to occur during the execution of most sys- tems. In order to accommodate this result, a ‘pro- cess model’ was sketched which aimed to support both pipelines and more complex control regimes in a flexible but structured way (see (Cahill et al., 1999),(RAGS, 2000)). In this paper, we describe our attempts to test these ideas in a simple NLG application that is based on a concrete realisation of such an architecture1. The RAGS …

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