Grounding GDMs:

A Structured Case Study

Enrico Motta*, Kieron O'Hara?, and Nigel Shadbolt?

*Human Cognition Research Laboratory,
The Open University,
Walton Hall,
Milton Keynes,
MK7 6AA.
U.K.

?Artificial Intelligence Group,
Dept. of Psychology,
University Park,
Nottingham,
NG7 2RD.
U.K.

International Journal of Human-Computer Studies, March 1994

Abstract

In this paper a solution to the Sisyphus room allocation problem is discussed,which uses the generalised directive model (GDM) methodology developed in the ACKnowledge project, together with the knowledge engineering methodology developed in the VITAL project. After briefly introducing these methodologies, the paper presents a "walkthrough" of the Sisyphus solution from analysis to implementation in detail, so that all acquisition, modelling and design decisions can be seen in context. The selection of a reusable off-the-shelf model from the GDM library is presented, together with a discussion of the ways in which this selection process can drive the knowledge acquisition process. Next,there is an account of the instantiation of the GDM and the imposition of a control regime over the dataflow structure; we show how this process uncovers hidden constraints and inconsistencies in Siggi's account of his own problem-solving. The output of this KA phase consists of a conceptual model of the problem which is discussed in detail and formalized in terms of the VITAL conceptual modelling language. From this analysis of the problem, we move on to discussion of the issues concerning the design and implementation of a system, and we show how our implementation satisfies the specification of the Sisyphus problem.