Parallel Mutual Exclusions

Applications of Petri net theory have been extended to various aspects of manufacturing since its introduction to this domain in the 1970’s. Among them are specification, validation, performance analysis, and simulation for automated manufacturing systems [Al-Jaar 90a; Desrochers 89; DiCesare 91; Murata 89; Silva 90; Zhou 90a]. One can also directly convert Petri net definitions into control code for supervisory control of manufacturing systems. Only after correct Petri net models are constructed for systems do all these applications follow. Therefore, the systematic modeling of a system is very important. Traditionally, one obtains a Petri net model using trial and error methods, and then analyzes it for properties like boundedness and liveness. Since in a moderately sized manufacturing system the complexity of design at the implementation level of detail easily becomes unreasonable, a challenging problem arises: that of systematically constructing a Petri net model such that it has the desirable properties for a manufacturing system.