Natural language understanding in road accident data analysis

Abstract Road accident records in Britain each comprise two components: coded data in a predefined format, and plain English in free format. This paper describes a natural language understanding system for information retrieval from the latter to verify and extend the former. We adopt the description logic system BACK to achieve a common representation of information from each of the two sources to facilitate comparison. A sub-category grammar is adapted to achieve automatic classification in BACK, and a bidirectional chart parser is adapted to operate with this grammar. This gives good independence between grammar rules, and provides flexibility, expressiveness, and the ability to resolve ambiguities.