From discrete to continuous models: A perspective on fluidization of Petri nets

The analysis and synthesis of Discrete Event “views” of dynamic Systems (DES), suffer of the so called state explosion problem. Petri net is a generic term used to designate a broad family of related formalisms for DES, all sharing some basic relevant features, such as locality of the states and actions, with consequences as temporal realism. This article deals with Place/Transition nets, by default simply called Petri Nets (PNs). A crucial property of PNs is that the global state of a system is numerically quantified, usually expressed in vector form. Among the most promising techniques to deal with the related computational problems are structural strategies as “divide and conquer”, of methodological nature, and fluidization, a relaxation. This invited contribution presents a quick overview of possibilities and problems with the last approach.