Generating Natural Language Explanations in a Computer-Aided Design System.
CONNECTICUT UNIV STORRS LAB FOR COMPUTER SCIENCE RESEARCH
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CADHELP is a graphics-based computer-aided design system which contains detailed knowledge bases intended to support three different types of intelligent behavior 1 the generation of natural-language explanations concerning the operation of the graphical features, for use by naive users 2 an animated display coordinated with the explanation, simulating the features use and 3 control of the operation of the CAD system itself, by interpretation of knowledge structures describing the systems operation. This final report is a detailed description of the knowledge-base summarization and generation methods developed for CADHELP, which are the basis for the three different sources of knowledge. The Explanation Mechanism devised for CADHELP describes the CAD commands CADHELP can execute using test and graphical animation. A unique feature of this system is that neither the text nor the animation are stored, but are generated from a representation of knowledge about how to use CADHELP. This representation, called a feature script, is a set of concepts linked by causal relations. Since the feature scripts developed were very detailed to enable the animator to work, a means of pruning the script to produce natural-sounding text was needed. A selector mechanism, called HELPCON, was developed to select concepts for expression from the feature scripts using rules on how to conduct an explanation. The concepts thus selected are generated as English sentences by another module called OGEN, which prunes a concept to express it in a concise form much as HELPCON does.