Intelligent Advisor

I need to write rules that says: The Person does not have blue eyes if the Person has brown eyes.

I know that I don't want to use a "not" in the conclusion and have it work right as a premise that is in the positive.

I want the interview to ask whether the person has brown eyes. If the answer is true, then "the person has blue eyes" is set to false. But if "the person has brown eyes" is false, then I want the interview to ask whether the person has blue eyes. I don't want to assume that the person has blue eyes, if the person doesn't have brown eyes.

I know this can be done, but can't remember how to do it. I tried a table for "the person has blue eyes" as the conslusion, setting it to false if "the person has brown eyes", but having Uncertain as the otherwise doesn't cause the question "does the person have blue eyes" to appear if the answer to the question "does the person have brown eyes" is false. It wouldn't parse if I use "unknown" as the otherwise.

Hope this makes sense.

Thanks,
Terry