An Expert System is a rule processing system. It has a large database of rules in the form or p->q, and uses the rules to answer questions. Most expert systems can also use Inference to establish more advanced rules, such as if p->q and q->x then p->x. Most expert systems are specialized to a specific domain, such as diagnosing health issues, or evaluating specific diseases. There are also general knowledge expert systems such as the Cyc project. Another project is Serapeum Expert System