Hierarchical reduction method for analysis and decomposition of Petri nets

A hierarchical reduction method for Petri nets is proposed. After a brief survey on the existing methods of Petri net reduction, concepts such as reducible subnet, degree of subnet, and macronode are defined. The subnets are partially ordered by the degree of subnet, and thus the reducible subnets can be reduced into the macronodes. A reduced net can be obtained without changing the properties (for example, liveness and boundedness). A sequence of reduction results in a hierarchy of reduced Petri nets that allow easy verification and hierarchical decomposition of the system.