E:/Doctorat/Raport tehnic/teza.dvi

Preface The aim of the workflow management is to help business goals to be achieved with high efficiency by means of sequencing work activities and invoking appropriate resources associated to these activities. Therefore, workflow management is both a key technology in supporting business processes and an effective means to realize full or partial automation of a business process. Despite many workflow management systems developed for different types of workflow processes, the lack of rigorous theoretic foundation and effective model verification and analysis methods in current workflow management systems is considered a serious problem. Correctness verification plays an important role in implementing successful workflow management. The objective of correctness analysis of process control is to avoid the deadloks or structural conflicts in the execution of a workflow model. Formal semantics, local state-based system description, and abundant analysis techniques are good reasons to use Petri net based workflow management systems. Time management in workflow processes is crucial in determining and controlling the life cycle of business activities. Time management involves the assignment of deadlines , checking of timing inconsistencies, or the calculation of the overall process duration. In this thesis there are discussed two main time extensions of workflow nets. Four types of timed workflow nets are introduced, L, E, S, and A, each of them based on the corresponding type of timed Petri net. The soundness property is studied for each type of them. In case of Land E-timed work-flow nets, the soundness property is equivalent with boundedness and liveness properties of their closures, which are Land E-timed Petri nets, respectively. Boundedness and liveness properties for L-timed Petri nets can be reduced to the same properties for classical Petri nets. Petri nets with zero tests ii on bounded places are introduced and boundedness and liveness of E-timed Petri nets are reduced to the same properties of Petri nets with zero tests on bounded places. The soundness property for Sand A-timed workflow nets is studied through the halting problem of deterministic counter machines: deterministic counter machine can be simulated by Sand A-timed workflow nets and the halting problem of deterministic counter machines can be reduce to the quasi-liveness property of Sand A-timed workflow nets. As a conclusion, our thesis closes the decidability status of the soundness problem for timed workflow nets with discrete time durations based on L-, E-, Sand nd A-timed Petri nets [56, 22]. I would like to thank all …