Resistive Networks Revisited: Exploitation of Network Structures and Qualitative Reasoning about Dev

For diagnostic purposes, analog circuits may be qualitatively modeled as resistive networks. We demonstrate that approaches to this task show certain weaknesses if they are based on sign-based qualitative values. In order to overcome these deficiencies, we first introduce qualitative deviation values with a semantics that enables us to model different classes of faults arising in analog circuits. The qualitative values adequately describe different effects that faults may have. Then we present a sound and complete inference algorithm for computing these effects using qualitative operators and local propagation techniques. *