Verification and reduction of cyclic structure in workflow model

As the foundation and focal point of workflow application, it is unavoidable to introduce the structural conflict during the establishing of workflow model. However, the currently existed verification method of workflow mode has limitations. An effective method that can be used to verify arbitrary workflow model is required. After the investigation of the workflow model, we find that the cyclic structure can make the workflow model more complex. Thus, this paper aims to investigate the cyclic structure of workflow nets (WF-net). The method for establishing the transition invariant (T-invariant) subnet of WF-net is proposed, then the necessary and sufficient condition for the T-invariant subnet with sound structure is given. In further study, a verification and reduction method of cyclic structure of WF-nets is put forward. This method not only can point out the error in the cyclic structure and find what causes the error, but also can reduce the sound cyclic structure. After the reduction, a WF-net with cyclic structure is reduced to a WF-net without cyclic structure, then many reduction methods can be used to realize the sound verification of a WF-net without cyclic structure. In the end, the time complexity of the verification and reduction process is discussed.