“…The notion of Self-Organized Criticality (SOC) was originally introduced by Bak, Tang and Wiesenfeld [4,5] starting from a basic example proposed as a model for sandpiles (we refer to [3,22,37] for a general introduction to this broad subject). Since then, the concept has been expanded in many different directions, spanning from classical topics of physics (sandpile avalanches [27], distribution of earthquakes [35,47], amplitude of solar flares [39]) to less standard economic and socio-political contexts [2,7,9,13,24,38,42,44,52], passing through computer networks and biological applications [1,40,53,15]. At the same time, a huge effort to extend the mathematical tools to deal with theoretical questions has been made, thus contributing to drive SOC into an extraordinary crossroads of probabilistic approaches, graph theory, algebraic geometry, mathematical analysis and optimisation [6,8,10,11,12,23,28,41].…”