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The expert system based on framework refers to the expert system which adopts the method of frame knowledge representation. It is based on the framework system and has good structural characteristics. Since the rise of framework-based expert system from 1980s to 1990s, it has been successfully applied in simulation, control and other fields.

The basic structure of the framework-based expert system is also similar to that shown in figure 10.1. The main difference lies in the representation and organization of knowledge in the knowledge base and the representation of facts in the comprehensive database. The reasoning method of the inference engine and the control strategy of the reasoning process of the system.

In the framework-based expert system, the knowledge base is composed of a framework system that represents the knowledge of the problem domain. The concepts and structures of frameworks and framework systems have been discussed in Chapter 2, which can be used to represent more complex structural knowledge.

The reasoning process of the framework expert system is mainly realized through the inheritance, matching and slot filling of the framework. When you need to solve a problem, you should first express the problem in a framework. Then, using the inheritance relationship between frames, match it with the existing frames in the knowledge base, find out one or more candidate frameworks, and under the guidance of these candidate frameworks, further obtain additional information and fill in as many slot values as possible. to create an example that describes the current situation. Finally, some evaluation method is used to evaluate the candidate framework to decide whether to accept the framework or not.

The feature inheritance of the framework system is mainly realized through ISA and AKO chains. When you need to query an attribute of something, and the framework that describes the thing does not provide its attribute value, the system traces back to the class or superclass framework with the same slot along the ISA and AKO chains.

The matching of the frame is actually realized by comparing the slot name and slot value of the corresponding slot one by one. If there is no contradiction between the corresponding slots of the two frames, or if some predetermined conditions are met, it is considered that the two frames can match. Because of the inheritance relationship between frames, some attributes and attribute values described by a framework may be inherited from the superclass framework, so the comparison of the two frameworks often involves the superclass framework, which increases the complexity of matching.

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