Discrete and fluid Petri nets: dealing with individuals, populations and fluidization

Two traditional ways to deal with the computational complexities of the analysis and synthesis of Discrete Event Systems (DES) are structural techniques and fluid relaxations. In the second case, the expected computational gains for analysis and synthesis problems are usually performed at the expense of the fidelity of the approximated model. Among the structural techniques, the abstraction of individuals into some populations may be very appealing. Using a basic examples-driven approach, the interest of the fluidization of DES models and of the aggregation of some local states by the decolorization of models (creation of populations) will be briefly illustrated.