Hierarchical Abstraction Process in Model-Based Diagnosis

Hierarchical diagnosis is an important method for reducing the complexity of model-based diagnosis.It is a significant step for hierarchical diagnosis to construct the hierarchical model of the system to be diagnosed.The previous methods have been based on some particular abstraction model.And they have not related the generic notion of abstraction to hierarchical process in model-based diagnosis and not formally analyzed the methods of automatically building the hierarchy of the system.The KRA(Knowledge Reformulation Abstraction) model provides a general framework from a view of constructive point which has potential to unite the former abstraction methods.The authors constructed the system model within the KRA model framework.This model provides a dependent operating process based on the basic framework Rg of the system.The process avoids producing a repetitious basic type and thus not only reduces space complexity but also makes the abstract operators reused more frequently to improve the performance of the whole abstraction operating.In this paper the authors describe the hierarchical abstraction process in model-based diagnosis and provide a general algorithm to automatically construct the hierarchical representation of the system to be diagnosed.The algorithm runs by building the operators database in two ways: Dynamic and Static whose advantage and disadvantage are also analyzed.In addition,the authors also discuss the validity and complexity of the proposed algorithm.