Petri charts: an alternative technique for hierarchical net construction

We present a new formalism for modelling concurrent systems, called Petri charts. It is based on Petri nets and statechart principles. It aims at benefiting from the power of both methods in order to provide a modelling method that has substantial expressive power and abstraction functionalities. These appear to be necessary for introducing a formal method into the field of modelling real-world applications. Intuitively, one can say that Petri charts enhance Petri nets by introducing depth: a place (transition) may be refined by a subnet, retaining the original place (transition) as a super-place (super-transition). Besides being a high-level modelling technique, Petri charts allow the combination net refinements and net composition operators, two mechanisms for the modular development of Petri nets. Basic formal definitions and the Petri chart method are presented. We also define a transformation on Petri charts yielding Petri nets. It enables the reuse of the available research results in the area of P/T nets, which is an important benefit