The program named AE/IE, is a simple inference engine¹, of the sort that might be used to develop an expert system² - AE/IE is like our Turing Machine³ simulator from Module 8 in that it is capable of processing any combination of rules⁴ and facts, so long as we describe them in a form that is acceptable to the program.

As you can see from the pre-loaded example, "Facts" are entered into the field to left of the program window as English phrases, and are designated to be T (true), F (false), ? (unknown) or G (a goal to be established) to indicate their initial condition.

"Rules" are entered in the field to the right by combining fact numbers to produce logical inferences. In our example, rule 1 can be interpreted as "If the power cord is plugged in AND the power switch is ON, then the machine is powered by AC." Once set in motion, the program proceeds through the rules applying all that are applicable (if either fact 1 or fact 2 is F (false), rule 1 is simply not applied, and no change is made to fact 7.)

1. Run the example rule base now by clicking on the "Play" button. What is the state of fact 7 after the rule base has been run? What does that tell you?
   
   
2. Reset the program, which changes the condition of all facts back to their original conditions (T, T, F, T, T, ?, ?, G, respectively).
   
   
3. Now, use the "STEP" button to proceed through the rule base one rule at a time. Pay close attention to the conditions of the unknown facts and of the goal. Which rules cause which facts to change conditions?
   
   
4. Reset the fact base to reflect the machine being powered by battery, instead of by AC. That is, set the fact condition 1 - 8 to (F, T, T, T, T, ?, ?, G, respectively). Step through the rule base. Which rules set which facts in this case?
   
   
5. Develop a set of condition values for the facts that would NOT lead the inference engine to the conclusion that the machine being tested was operational (so that the goal rule can not be determined). Run the rule base on your set of conditional values to see if it performs as expected.