Nets within nets

[5] The earliest use of such hierarchic net models appeared by Rüdiger Valk in Valk and Jessen,[6] where the so-called task-flow nets[7] are introduced in order to model task systems in operating systems.

[11] In distributed token semantics the important calculus of place invariants for Petri nets remains valid.

Like in object-oriented programming communication of net tokens is introduced via predefined interfaces which are dynamically bound.

Standard Petri net properties like reachability, boundedness and liveness show a mixed picture.

To reduce the complexity of the formalism subclasses have been defined by restricting the structure of the Petri nets, as for instance to state machines.