Definition of deadlock patterns for business processes workflow models

To support deadlock detection by computer, five patterns which cause deadlock are defined. In expressing the pattern of deadlock structures by control-node combinations only, it is difficult to express the connection properties, since these are decided by many complex combinations of control nodes. Therefore, two new concepts, "reachability" and "absolute transferability", which express connection properties between two control nodes, are introduced. With these concepts, the five deadlock patterns are expressed simply. It is demonstrated mathematically that all deadlock structures can be classified into these patterns and that deadlock occurs in business process workflow models which have one or more of these patterns.