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UC is a natural language computer consultant system for the UNIX operating system. The user model in UC encodes the user's knowledge state and allows UC to tailor its responses to the user. The model encodes apriori knowledge in a double stereotype system that is extremely efficient. Models of individual users are updated dynamically and build on top of the user's stereotype. The model deals with uncertainty in apriori information and attempts to deduce the user's level during the course of a session.
David N. Chin (Tue,) studied this question.