statements “Socrates is a man,” “All men are humans,” and “All humans are mortal.”
There we see the body of knowledge shifting from one state to another as the reasoning
process applies appropriate productions to generate additional statements.
Today, such reasoning systems, often implemented in logic programming languages
(Section 6.7), are the backbone of most expert systems, which are software
packages designed to simulate the cause-and-effect reasoning that human experts
would follow if confronted with the same situations. Medical expert systems, for
example, are used to assist in diagnosing ailments or developing treatments.