Abstract: An expert system includes a knowledge base manager which is fact-based, as opposed to rule-based; i.e., a semantic network with tangled hierarchies. The system includes an inference engine which is capable of providing solutions to indeterminate problems with a high degree of confidence. "Entities"(e.g., propositions, fact and ideas) are understood in eight different ways depending on the context of entity relationships. Each such relationship may be characterized anywhere along a spectrum from strong to weak. The knowledge base is designed so that entities and relationships are easily modified. The analysis performed may be at any of various levels of detail. The system can accept data as keyed input as well as from independently executed programs. Results developed by the inference engine are presented in various levels of detail in terms of relative degree of agreement or divergence from anticipated conclusions and the inference engine's degree of confidence in the results.