Ensemble Engineering and Emergence

The complex systems lying at the heart of ensemble engineering exhibit emergent behaviour: behaviour that is not explicitly derived from the functional description of the ensemble components at the level of abstraction at which they are provided. Emergent behaviour can be understood by expanding the description of the components to refine their functional behaviour; but that is infeasible in specifying ensembles of realistic size (although it is the main implementation method) since it amounts to consideration of an entire implementation. This position paper suggests an alternative. ‘Emergence’ is clarified using levels of abstraction and a method proposed for specifying ensembles by augmenting the functional behaviour of its components with a system-wide ‘emergence predicate’ accounting for emergence. Examples are given to indicate how conformance to such a specification can be established. Finally an approach is suggested to Ensemble Engineering, the relevant elaboration of Software Engineering. On the way, the example is considered of an ensemble composed of artificial agents and a case made that there emergence can helpfully be viewed as ethics in the absence of free