Easy synchronized Petri nets as discrete event models

Linguistic concepts are introduced to relate Petri net models with the control theory for discrete event systems. Petri net structures can be considered as language generators, and different languages associated with them are examined. An important operator, synchronization, is introduced and its counterpart on a Petri net structure is studied. Finally, the authors introduce the concept of easiness, and study how this property is preserved by synchronization. A net is easy when the solution of the state equation gives a sufficient condition for reachability. The main result is that, although easiness is not preserved in general by synchronization, one can define classes of synchronization that are easiness-invariant