Ill-Structured Domains

An ill-structured domain is a domain where there are concepts, but the way those concepts are instantiated in the real world are hugely variable, and messy as hell. Business, medicine, arts ...

Ex ... heart attacks: A heart attack is a concept. It is a thing you can study in medical textbooks. But actual diagnosis of heart attacks can be hugely variable — it depends on the patient’s race, age, gender, case history, potential complications, and so on; some heart attacks present as indigestion initially, others may last days.

In these domains the experts look more like artist than scientists.