  Models and simulations of collective behaviours are often based on
considering them as assumed by interactive particle systems. The focus is then
on behavioural and interaction rules by using approaches based on artificial
agents designed to reproduce swarm-like behaviours in a virtual world by using
symbolic, sub-symbolic and agent-based models. A new research approach has been
introduced based on meta-structures, i.e. variable structures of mesoscopic
variables possibly suitable for a general theory of emergence. In this approach
I consider the coherence of collective behaviours, i.e., their identity
detected by the observer, as represented by meta-structures. Meta-structures
are properties of meta-elements, i.e., sets of values adopted by mesoscopic
state variables describing collective, structural aspects of the collective
phenomenon under study and related to a higher level of description
(meta-description) suitable for dealing with coherence. Mesoscopic state
variables are abductively identified by the observer detecting emergent
properties, such as sets of suitably clustered distances, speed, directions,
their ratios and ergodic properties of sets. Simulation software is under
implementation. We present four research projects based on such an approach
able to give the reader the perspective applications.
