Review of hierarchy in Petri Nets

Petri nets are increasingly being used to create IT and automation systems whose high complexity requires a new approach to design and implementation. As a result, new concepts for describing, analyzing, and presenting Petri nets have been developed, among which the introduction of a hierarchical network structure holds an important place. This structure allows for the presentation of a created system (network) at various levels of abstraction and facilitates the determination of the properties of its modules (subnetworks) and the all network. Although hierarchical networks are currently widely used in research and pracital applications, there is no uniform way of using them. Therefore, the aim of this article is to identify and present the basic concepts of applying hierarchy in Petri nets.