Construction of Petri nets via states of action objects and subjects

We consider three ways of constructing Petri nets. The first, most reliable way is to use all states of action objects and subjects. The Petri net constructed in this way is considered as the "correct" Petri net for verifying other nets. Then we construct the Petri net via states of action objects only with some constraints. In this case we implement constraints as the guaranteed boundedness of the number of tokens in selected places and find that the resulting Petri net coincides with the "correct" one. We show that the Petri net via states of action subjects with constraints also coincides with the "correct" Petri net. We also consider an example illustrating the fact that specifications of systems to be modeled via states of action objects only or action subjects only with related constraints are more natural and convenient as compared with specifications via states of action objects and subjects.