"An experimentation strategy directed by kinetic logic"
Kinetic logic appears as an interesting simplification of complex sytems with feedback loops. It takes time and thresholds of activity into account and allows to find all steady states stable and unstable as previously shown (Snoussi and Thomas 1993, Thomas 1993). The first description is a graph accounting for the different elements of the system, their interaction with a few strength levels, and sometimes environment, represented by external variables. Kinetic logic, a method easily accessible to biologists or physicians, with one unique hypothesis, the existence of threshold(s) of activity for each variable, allows to write semi-logical equations and to construct state tables. Then, it takes time into account through various on- and off- delays and leads to the prediction of the elements apparition/disparition. Therefore this method seems to be convenient for building simplified models related to infectious diseases, where several feedback loops occur. This implies usually qualitative predictions concerning the dynamics of such biological systems, leading to a movement back and forth between experimentation or observation and logical description. After a rapid description of the method, we will illustrate it and show how these elementary models applied to several viral diseases, allow predictions experimentally verified. Snoussi, E.H. & R. Thomas (1993). Logical identification of all steady states : the concept of feedback loop characteristic states. Bulletin of Mathematical Biology 55: 973-991. Thomas, R. (1993). Logical identification of all steady states. In: J. Demongeot and V. Capasso (ed.), Mathematics applied to Biology and Medicine, pp. 345-357. Winnipeg, Canada, Wuerz Publishing Ltd.