On the Emergent Behavior Oxymoron of System-of-Systems Architecture Description

A major research challenge for the design of a software-intensive System-of-Systems (SoS) is the formal description of its software architecture. The main complicating factor is that an SoS, by definition, has its architecture designed to produce emergent behavior for fulling missions. But, by definition, an emergent behavior is an "unexpected" behavior. By "unexpected", we mean a behavior of a whole (i.e. the SoS) that cannot be predicted through analysis only of its parts (i.e. the constituent systems of the SoS), or stated simply: the behavior of the SoS is other than the sum of the behaviors of its constituent systems. The oxymoron is thereby: how to formally design and describe the software architecture of an SoS to exhibit "expected" (by design) "unexpected" (emergent) behaviors that stem from the interactions among the constituent systems of the SoS? To address this oxymoron, this paper investigates the notion of emergent behavior for clarifying the boundaries of this notion for SoS and then presents the architectural emergentist framework that we developed to enable the architectural description of emergent behavior of software-intensive SoSs.