Editorial: "Complexity of systems evolution: Requirements engineering perspective"

This introduction discusses the changing nature of complexity associated with requirements engineering (RE) tasks and how it has shifted from managing internal complexity to adapting and leveraging upon external and dynamic complexity. We note several significant drivers in the requirements knowledge that have resulted in this change and discuss in light of complexity theory how the RE research community can respond to this. We observe several research challenges associated with "new complexity" and highlight how the articles included in the special issue advance the field by defining complexity more accurately, observing more vigilantly new sources of complexity, and suggesting new ways to manage complexity in terms of economic assessments, knowledge flows, and modeling for adaptability.