Towards Automating Explanations

Abstract

This paper discusses an approach to the modelling of the explanation process within the framework of a graphics-based CAD system currently under development, which can describe its own use, including the common ways to make and recover from errors. With a coordinated textual and pictorial display, the system, CADHELP, simulates an expert demonstrating the operation of the graphical features of the CAD tool. It consults a knowledge base of feature scripts, built up using situational script and commonsense algorithmic methods, to explain a feature, generate prompts as the feature is being operated, and to give certain types of "help" when a feature is misused. CADHELP provides these services by summarizing the feature script in different ways depending upon what it has told the user previously. The summarization process is based upon a series of "sketchification" strategies, which prescribe which parts bf a knowledge structure, a causal chain, or a single concept can be thrown away, since the listener should be able to infer them.