Flex

Flex is a very powerful and versatile expert systems toolkit. In contrast to simple expert system shells, Flex offers an open-ended knowledge-based solution to business problems.Flex is implemented in Prolog, a high-level rules-based language, and has unlimited access to the power of that underlying technology.The success or failure of a software development platform depends to a large extent on the unique features it offers. Flex is a wonderful platform evolving to greater heights each time a new version is created.