Necessary and sufficient conditions for deadlock in manufacturing systems

Scheduling resources to avoid deadlock in a manufacturing system has been studied extensively over the past decade: Previous work developed sufficient conditions to avoid deadlocked states. What distinguishes the different approaches is the number of non-deadlocked states that are allowed by the application of the method. This is an important consideration since in all the methods these non-deadlocked states are those with high resource allocation. This paper presents both sufficient and necessary conditions to determine deadlocked states in a manufacturing system. Several examples showing the applications of the theory are presented and are compared with other methods.