A requirements description language pLSC for probabilistic branches and three-stage events

The language of Live Sequence Chart (LSC), a multi-modal extension of MSC, introduces the distinction between mandatory and possible on the level of the whole chart and for the chart elements. While the LSC still extend the MSC qualitatively, when it comes to capturing the quantitative behaviors, the deficiency emerges. As for the probabilistic systems, i.e., systems that exhibit probabilistic aspects, probabilistic properties are considered as the most important requirements and need to be captured quantitatively. To address this, we propose a requirements description language called pLSC. Supported by the measure theory and the probability theory, the language pLSC describes the interactions quantitatively to suit the probabilistic systems from two dimensions of probabilistic branches and three-stage events. The paper introduces the graphical and textual presentation of the pLSC.