Place/Transition Systems

In the 1970ies, Place/Transition Systems were certainly the most common and the most extensively studied class of nets. Often they have just been called Petri Nets.We introduce their basic concepts, viz. the idea of places that carry any number of (identical) tokens. This introduces a dimension of infinity that implies a lot of interesting theoretical problems such as liveness, boundedness and the reachability of markings.We especially stress the viewpoint of General Net Theory, considering such nets as shorthand notation for elementary net systems. In this way the rich body of theory for c/e systems is applicable also for place/ transition nets. Finally we will study net properties that can be derived from coverability trees.