Intelligent agent is an artificial intelligence system, explains Das, and an epistemic state is an actual or possible cognitive state that drives human behavior at any given moment, and must be simulated by an intelligent agent for it to simulate human behavior. He describes three broad and fundamental approaches--logical, probabilistic, and modal--to representing and reasoning in the context of decision making. His study could be used as a textbook in a graduate or undergraduate course on artificial intelligence, or as a reference for researchers.