Detecting overlapping use cases

To deal with the complexity of large information systems, the divide-and-conquer policy is usually adopted to capture requirements from a large number of stakeholders: obtain requirements from different stakeholders, respectively, and then put them together to form a full requirement specification. One of the problems induced by the policy is overlapping requirements. A use case driven approach could not avoid overlapping requirements either: it produces overlapping use cases, which are even more harmful, because a use case describes not only inputs and outputs as traditional requirements do, but also the scenarios. Each of the overlapping use cases provides a message sequence to implement the common subgoal. Overlapping use cases not only decrease the maintainability of the requirement specification, but also result in a complicated, confusing and expensive system. To be worse, it is difficult to detect overlapping use cases with existing methods for requirement management. To find out overlapping use cases, a detection approach using sequence diagrams and statecharts is proposed. Evaluation results suggest that practical requirement models do contain overlapping use cases, and the proposed approach is effective in detecting them.