VERIFICATION AND VALIDATION OF LARGE RULE BASES

Due to successive refinement and improved functionality, advanced prac tically applied expert systems steadily grow with respect to number of rules and complexity of their interrelation. This effects, that more and more the transparency of reasoning at run time as well as the surv ey over the consistency of the rule base in amendment are lost. To ove rcome these problems for an existing large expert system, a debug and trace system has been developed which combines formal consistency chec k functions with convenient explanation facilities, making use of the rules' potential and actual connectivities as well as the implemented inference mechanisms A hypothetical mode enables to check the conseque nces of decisions in advance. The resulting functionality is in partic ular suitable to facilitate the knowledge base verification and valida tion with respect to logical consistency and semantic contents. Beside s, the extended explanation capability is also useful for the expert s ystem's user at run time.