1. In an expert system with a frame explanation system for inputting and uninterrupted processing of facts comprising: means for inputting facts to the system; an inference engine comprising means for analyzing the facts and drawing inferences from the facts; means for storing a rule base containing rules used to analyze the facts, said rule base being grouped into rule classes, each class containing one or more rules; means for storing a dependence table which solely defines the relationship of the rule classes to one another; means for firing a first rule in a class when an inference is drawn from the facts; an explanation system comprising means for storing explanations associated with each rule class, the explanation system including means for creating a series of frames and storing in a frame one or more explanations when the first rule in a class is fired; and means for displaying conclusions generated by the expert system from the inputted facts and related explanations as an output from the expert system.