Using expert systems to solve complex problems

Can expert systems solve complex problems? Yes. But they’re not born to do it. Humans need to create the knowledge base that will enable them to reason about complex problems. The process is called knowledge engineering.

Human experts hold knowledge in their domain of expertise. Knowledge engineers are the ones who acquire this knowledge and put it into an expert system’s knowledge base.

The more complex the domain, the more complex the knowledge will be. But the knowledge engineer can’t only focus on the complex knowledge because expert systems have no common sense.

Let’s work through an example. Imagine you find someone on a sidewalk. Your problem is that you don’t know what to do.


Using conditional if…then logic, an expert system might help you solve the problem.

If the subject doesn’t respond to pinching, gentle shaking or shouting, then the subject is not conscious.

If the subject has no visible signs of severe bleeding, then perform a head to toe examination of the subject for other signs of trauma.

If not visible trauma is found, then begin a neurological assessment of the subject.

If the subject’s pupils don’t constrict immediately when a bright light is shone into its eyes, the subject may have suffered a neurological trauma and should be examined immediately by a physician.

If we have good expert knowledge available, we can keep going.

If the physician repeats the tests above on the subject and the subject doesn’t respond, then the physician should perform oculovestibular testing on the subject.

If the physician is performing oculovestibular testing on the subject, the physician will irrigate the subject’s ear canal with an iced saline solution.

If the subject does not exhibit nystagmus (involuntary rapid eye movements) in response to the oculovestibular testing, then the subject is likely to have a severe brain stem injury.

A knowledge engineer creating this knowledge base would have to cover off multiple common sense issues to help the expert system solve this problem. For example, we’d need to know very early in the assessment if the subject had a pulse or appeared to be breathing. There’s no point in performing neurological assessments on someone who’s dead.

An expert system with a knowledge base full of very advanced medical knowledge is still going to have to cover basic common sense reasoning.

Expert systems can solve complex problems. Humans have to build them to handle the easy ones too.

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