Abstract
The problems of recent approaches in qualitative and causal reasoning include; (1) In qualitative modeling, they do not discuss on what types of mathematical models their qualitative equations should be based. This causes them to misuse static models for the qualitative equations to discuss changes in the transient state. (2) Many of them use causality which does not refer to time explicitly. Then, in reasoning, they substitute logical inducibility or mathematical derivability for the causality. Such causality may include undesirable characteristics for producing causal accounts for physical systems.
In this paper, we define the “inherent causality” which requires “time reference”. With this causality, causal reasoning is carried out by verifying that any change is made by the causality. The verification is done by the requirement of dt=+ for each step. In order to make such causal reasoning possible, we carefully choose the base model, i.e. the dynamical model which describes causality from what makes the change to what is changed. We also developed the qualitative simulation algorithm with the inherent causality. The power of the causality and simulation algorithm is demonstrated on two examples of the pressure regulator and the mass-spring system.
