Design and evolution of sociotechnical systems. A requirements engineering perspective

Sociotechnical systems are systems of systems where social, technical, and organizational systems interact with each other to satisfy their requirements. The interplay of social and technical systems blurs the borders in between them, and the constant change within and outside the sociotechncial systems create difficulties to manage the overall evolution. This thesis explores the methods to model, analyse, and evolve the requirements of sociotechnical systems. We propose a systematic design process and a formal language to aid social systems refine their requirements into not other requirements but also social interactions to generate system as well as interaction specifications. Although such specifications are useful to generate interaction protocols among systems, they haven’t been investigated in detail by the requirements engineering community. We then explore the design space created during the design process with artificial intelligence planing to discover sequence of actions to satisfy requirements with minimal cost. We adopt an iterative approach for handling requirements evolution and focus on the problem of selecting the optimal set of requirements for the next release. We capture synergies among requirements in goal-oriented requirements models and transform the next release problem into a multi-objective satisfiability modulo theories/optimization modulo theories problem and solve it using an external reasoner. We apply a similar approach for risk analysis using goal models. We model goals, risks, and treatments in three layers and solve multi-objective risk analysis problem with SMT/OMT reasoning. We evaluate our proposal with self-evaluation studies, a case study and scalability experiments and report results. The novelty of these two approaches is the combination of satisfiability analysis with multi-objective optimization for goal models.