Abstract
The capacity Petri net, which is a subset of general Petri net and each of its places can have at most a constant value called place capacity, is a suitable model for describing real systems' behavior.
Liveness analysis of capacity Petri net which represents system's behavior is important to guaranteee that the system is deadlock free. Capacity Petri net has essentially boundedness in marking, so its liveness problem can be completely determined by reachability tree analysis. However, procedure of making reachability tree needs a large amount of calculation time in proportion to net size power, so there is a practical difficulty that only small size net can be analyzed by reachability tree.
Several reduction algorithms of general Petri net which has no limit of place capacity was proposed to relieve this difficulty. However these algorithms don't take into consideration of place capacity, so they can't be directly applied to reduction of capacity Petri net.
In this paper a new reduction algorithm that can reduce capacity Petri net keeping its structual property of liveness with calculation time in linear proportion to net size. This algorithm has been experimentally applied to several capacity Petri nets which represent sequence control specifications of automatic machine tools. After reduction, their net size have become 1/2-1/10 compared with that of original net, and it has been proven that proposed reduction algorithm makes liveness analysis of capacity Petri net easier.
