A Qualitative Model of Physical Fields

A qualitative model of the spatio-temporal behaviour of distributed parameter systems based on physical fields is presented . Field-based models differ from the object-based models normally used in qualitative physics by treating parameters as continuous entities instead of as attributes of discrete objects . This is especially suitable for natural physical systems, e.g . in ecology . The model is divided into a static and a dynamic part . The static model describes the distribution of each parameter as a qualitative physical field . Composite fields are constructed from intersection models of pairs of fields . The dynamic model describes processes acting on the fields, and qualitative relationships between parameters . Spatio-temporal behaviour is modelled by interacting temporal processes, influencing single points in space, and spatial processes that gradually spread temporal processes over space . We give an example of a qualitative model of a natural physical system and discuss the ambiguities that arise during simulation .