Receding capabilities in systems of systems

Systems of systems are characterized by their dynamic behavior, exhibiting evolving emerging capabilities as new members join the family. Yet, little has been said on the possibility of some members leaving the system of systems, with the impact that it might have on the emerging capabilities experienced by some members of the family. At the same time, growing attention is given to the need for establishing a sound foundation for the field of systems engineering, with the development of the appropriate theories and methods, which require effectiveness definitions and metrics, among others. This paper introduces the concept of receding capabilities of a system of system, as a necessary building block to further complement and develop the foundation of systems engineering. The necessary concepts and defined and a proposed formulation is presented to capture the likelihood and impact of receding capabilities. A notional example is presented to illustrate the presented concepts.