Problem localization Is the identification of the most slgnlflcant failures i n the AND-OR tree resulting from an unsuocass/ul attempt to achieve a goal, for instance, In planning, b a c k w a r d - c h n i n i n g inference, or top-down parnin~ We examine beurlstics and strategies for problem localization in the context of using a planner to check for pragmatic failures in natural language input to computer systems, such as a cooperative natural language interface to Unix .
