A computer system for automatically defining and registering rules, conditions, judgment standards for business purposes, or coping strategies from experiences as business rules and making complicated business judgments on the basis of a combination of such business rules is called a business rule management system (BRMS) and is used for, for example, credit or insurance examinations in the financial industry, or bill calculation based on complicated discount plans for cell-phone bills. The business rules are defined in a production rule (if-then rule) format of “if . . . , do . . . (or do not . . . ).” Conventionally, an expert called a knowledge engineer is required to set the business rules; however, the business rule management systems in recent years can register and change the business rules by using a natural language and a mechanism for, for example, excluding conflicting business rules, so that even persons who do not have specialized knowledge can operate the business rule management systems. A product called JRules provided by IBM is known as such a business rule management system.