Problem solving and decision making by humans is often done in environments where
information concerning the problem is partial or approximate. AI researchers have been
attempting to emulate this capability in computer expert systems. Most of the methods used
to-date lack a theoretical foundation. Some theories for handling uncertainty of information
have been proposed in the recent past. In this paper, we critically review these theories. The
main theories that we examine are: Probability Theory, Shafer's Evidence Theory, Zadeh's …