The Wikipedia article isn't a bad start. https://en.wikipedia.org/wiki/Expert_system https://en.wikipedia.org/wiki/Expert_system I have previously built an ex

The Wikipedia article isn't a bad start. https://en.wikipedia.org/wiki/Expert_system https://en.wikipedia.org/wiki/Expert_system I have previously built an expert system - a system of codified expert human knowledge built into a system of executable, interrelated rules. Rule engines are the execution engines of expert knowledge in an expert system. The RETE algorithm is another good place to start. https://en.m.wikipedia.org/wiki/Business_rules_engine https://en.m.wikipedia.org/wiki/Business_rules_engine https://en.m.wikipedia.org/wiki/Inference_engine https://en.m.wikipedia.org/wiki/Inference_engine https://en.m.wikipedia.org/wiki/Rete_algorithm https://en.m.wikipedia.org/wiki/Rete_algorithm When I was first learning, I downloaded and played with CLIPS, a pretty cool old expert system tool built by NASA. https://en.m.wikipedia.org/wiki/CLIPS https://en.m.wikipedia.org/wiki/CLIPS