David Harel, Shahar Maoz. Assert and negate revisited: modal semantics for UML sequence diagrams. In Jon Whittle, Leif Geiger, Michael Meisinger, editors, SCESM 06: Proceedings of the 2006 International Workshop on Scenarios and State Machines: Models, Algorithms, and Tools, Shanghai, China, May 27, 2006. pages 13-20, ACM, 2006. [doi]
Abstract is missing.