Constructive and Non-constructive Asynchronous Simulation

From its inception it was known that qualitative reasoning had a problem with the generation of spurious behaviours, and a great deal of effort has been expended in tackling this problem . Two approaches have been taken to constraint based qualitative simulation : constructive and non-constructive, though a thorough and objective examination of the operation and results of performing qualitative simulation by means of these two approaches has not been carried out . The context of the work presented here is fuzzy qualitative reasoning . The two systems FuSim and Alycroft are used to compare non-constructive, semiconstructive and constructive approaches ; and the results of this are described and analysed . A number of conclusions are drawn, the most important of which is confirmation of the idea of "horses for courses" . It is plain that a causally ordered model reveals the interactions of the relations in a straightforward manner and constructive qualitative analysis gives an efficient initialisation process, which may be useful for diagnosis or explanation . On the other hand, nonconstructive approaches permit the simulation of systems which contain algebraic loops .