Qualitative Modelling Of Environmental Processes

The majority of our mathematical models is quantitative, i.e. expressed by quantitative, numeric relationships, although in our minds we usually think in a qualitative way, i.e. express relationships in a relative, descriptive way. We think in terms of how the change of a property affects the other properties of the system. In our minds we do not use differential equations to recognize that a ball thrown in the air must come down, or that bacteria will grow on a suitable substrate for some time and then die-off after all the food is eaten. An artificial intelligence (AI) approach is described which mimics this kind of reasoning. Examples of qualitative models from basic physics (throw of a ball) and environmental processes (microbial growth Monod's equation) are given and discussed.