Handling Ill-Formed Input: Session Introduction

In natural language access (e.g. English access) to information systems, the magnitude of the problem of absolute ill-formedness can be seen in several case studies. If one includes telegraphic and elliptical constructions in the class of absolute ill-formedness, then case s~udies reported in Thompson (1980) and Eastman and McLean (1981) indicate that as much as 25% of queries to questionanswering systems are absolutely illformed. On the other hand, no matter how large the dictionary, grammar, and underlying system, there will always be unknown words and phrases (e.g. proper names) and impossible requests (due to user misconceptions of the capabilities of the underlying system).