PURPOSE: To easily transform a subject world into a model by adding a procedure to a schema together with addition of a schema memory area so that an inference mechanism is provided on the schema.

CONSTITUTION: A schema gathering SDB3 including an inference engine IE2 and plural memory areas is prepared in response to a rule gathering RS1 containing IF and THEN. Not only the value but also the procedure is sometimes described in the memory area and a procedure executing means 7 holds the executing result added to the SDB3 in a memory area 8. A fact is held by an FDB4 and a control means 5 controls the IE2 to perform a communication job 6 between gatherings RS1. When a patient is diagnosed by three doctors and a blank space of a schema is filled with the conclusion, the doctors 1 and 2 substitute the diagnosing facts RS1 and RS2 based on a fact M related to the human begins, e.g., the body heat. While the doctor 3 inquiries a fact RS3 including an inference engine to draw some conclusion. Then a disease name M of the patient is decided through a prescribed logical procedure.