Event-Sequence Method for Qualitative Circuit Analysis

Abstract

To make qualitative reasoning about the dynamic behavior of a target system, simulation-based qualitative analysis has been developed. In this approach,the analysis starts with the initial state and generates new states one after another. A state is determined when every variable is assigned its value. Since a qualitative value is abstract and has less information compared with a numerical value, many variable values cannot often be determined. In such a case, simulation proceeds by hypothesizing every possible new states. This causes the combinatorial explosion of the system states when a complicated system such as circuits is analyzed. To alleviate this deficiency, we propose "Event-Sequence Method" which has the following characteristics: (1) A state is determined only through known variable values. (2) Simulation is performed for each sequence of causally connected events. We also present a qualitative circuit simulator QCS which is based on Event-Sequence Method and explains the dynamic behavior of electronic circuits.