Transformations and Decompositions of Nets

We present a set of transformations of place/transition systems which preserve several classical properties of nets namely boundedness, deadlock freeness, liveness and covering by S-invariants. These transformations may simplify or refine a system and allow either to simplify a place/transition system before analysing it or to introduce more details in a given system having some propreties without changing them. We also present a decomposition technique to split a system into subsytems which can be analysed separatly.