Which formal assumptions are basic in psychological models for the representation of individual knowledge? Which models are currently in use for different aims and domains? How can an individual's knowledge be assessed economically in view of careless errors? How can a computer procedure for assessing the metaknowledge of an expert be devised? What kind of principles can be applied for constructing problems? What is the exact definition of a rule-based system? What kind of experiments can be derived from different semantic structures and how are they related? This book offers many examples, exercises and illustrations for studying and answering such questions.