20. A knowledge system comprising a computer having a memory, said memory storing a knowledge base capable of being interpreted by a knowledge base interpreter to solve specified problems pertaining to a subject domain, said computer further comprising an authoring system for designing an evaluation procedure, said authoring system comprising means for analyzing the content of said knowledge base to determine a set of interrupt conditions for interrupting said interpreting of said knowledge base when said conditions occur to thereupon initiate said evaluation procedure, and means for designing said evaluation procedure for comparing knowledge about a subset of said interrupt conditions to knowledge obtained from a subject system.
27. The knowledge system as claimed in claim 20, wherein said knowledge base includes rules which conclude values for expressions, said rules including rules containing variables, and said means for analyzing includes means for determining conclusions a rule with variables can make, and means for instantiating said variables to determine expressions that can be included in the premises of said rules.