Expert system with a frame explanation system

• US 5,408,587 A
• Filed: 07/20/1992
• Issued: 04/18/1995
• Est. Priority Date: 08/28/1991
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Mueller, Claudia, Maier, Franziska, Saelens, Serge
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): Dorvil, Richemond
• Application Number:
  US07/916,923
• Time in Patent Office: 1,002 Days
• Field of Search: 395/51, 395/54, 395/10
• US Class Current: 706/46
• CPC Class Codes: G06N 5/045 Explanation of inference; Explainable artificial intelligence [XAI]; Interpretable artificial intelligence

Abstract

An explanation system for use in an expert system is described. The rule base used in the inference engine of the expert system is divided into groups of rules called rule classes. With each rule class, three types of explanations are associated: strategy explanations, reason explanations and inference explanations. The rule classes are arranged in a hierarchical explanation tree structure. Each time a first rule is fired within a rule class, a frame is created into which the explanations relating to that rule class are copied. After the completion of the reasoning process, the frames can be used to generate an explanation of the reasoning process.

Claims

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.

2. The expert system of claim 1 and further comprising means for modifying the dependence table to change the relationships of the rule classes to one another.

3. The expert system of claim 1 and further comprising means relating the frames to one another in a tree structure of nodes according to the dependence table.

4. The expert system of claim 3 further comprising means for placing an explanation in a frame corresponding to a node when a related rule is fired.

5. The expert system of claim 4 and further comprising means for storing strategy, reason and inference explanations in a frame.

6. In an expert system for inputting and uninterrupted processing of facts, a method of producing explanations comprising the steps of:

(a) inputting facts for processing in an inference engine;

(b) searching a rule base grouped into rule classes, each rule class containing one or more rules, the rule classes being related to one another in a dependence table and wherein the rule classes are arranged in a tree structure of nodes;

(c) firing a rule selected by the inference engine from the facts;

(d) determining whether the fired rule is a first fired rule in a rule class;

(e) if the fired rule is a first fired rule in a rule class, creating a frame for the rule class of the first fired rule;

(f) adding to the created frame one or more explanations related to the rule class of the first fired rule;

(g) analyzing the facts with the inference engine for any further rule which can be fired and repeating steps (b) through (f) until no more rules remain in the rule base to be fired; and

(h) outputting conclusions and explanations generated by the expert system from the inputted facts.

7. The method of claim 6 further comprising the step of placing each created frame at a node in the tree structure related to the fired rule.

8. The method of claim 7 further comprising the step of adding an inference explanation to the frame of the rule class of the fired rule.