This paper examines the role of case-based reasoning in a problem-solving assistant system, which differs from an autonomous problem solver in that it shares the problem-solving task with a human partner. The paper focuses on the criteria driving the system designer's (or the system's) choice of cases, of representation vocabulary, and of indexing terms, and upon how the assumption of a human in the problem-solving loop influences these criteria. It presents these theoretical considerations in the context of work in progress on lOPS, a case-based intelligent assistant for airline irregular operations scheduling.
