[Applications of a simple system of aid to medical decision-making with various patients in internal medicine: SELF].

Many medical decision helping systems are very complex and require expensive computers, which restricts their diffusion and limits their use to specialized people. The idea was to find a simplified system that any practitioner--even unaccustomed to microcomputing--would be able to use. Moreover, this system had to work on widely available and inexpensive microcomputers. SELF (system in fuzzy set) is this kind of system. It has been devised as a complete interactive system of medical decision help. It is entirely parameterized, allows any kind of application and works according to such rules as "if there is premise, then there is conclusion", tempered by a coefficient. The bases of knowledge are represented on a correspondence chart where columns materialize the premises (clinical signs, laboratory results, etc.) and horizontal lines all the diagnoses and therapeutic conclusions. The system includes proceedings that create, modify and update basic knowledge. It uses the fuzzy set rules to draw conclusions. SELF was first applied to the prescription of contraceptive methods, but it has now been tested in other specialties, such as gynaecology, pneumology, haematology and so forth. In every case, the reliability of the results obtained depends on the bases chosen by the creator himself. Owing to the general character of the system, one may regard it as being open to any user who would like to create his own applications.