Abstract
In this contribution, we consider Collective Behaviours as coherent sequences of spatial configurations adopted by agents interacting through corresponding different structures over time. The approach relates to the one adopted time ago when introducing the concept of multiple systems arising when each composing element can play simultaneously or sequentially different roles. In this case, each element simultaneously or sequentially belongs to different systems. Multiple structures over time and their sequences are considered as meta-structures establishing coherent sequences of different systems. They are intended as coherent when acquiring emergent properties. Such coherence is considered here as being represented by the values adopted by suitable mesoscopic variables and their properties, i.e. meta-structural properties, allowing the researcher to (a) recognise a phenomenon as emergent, (b) induce emergence of collective behaviour in populations of elements collectively interacting, (c) act on collective emergent phenomena with the purpose to change, regulate and maintain acquired properties and (d) merge different collective emergent phenomena. We introduce a formal tool, i.e. the mesoscopic general vector to represent the adoption, over time, of mesoscopic properties by collectively interacting elements. We mention future experimental lines of activities, future lines of research and possible applications.