“…The ASM was introduced (in the special case of the two-dimensional square lattice) by the physicists Bak, Tang, and Wiesenfeld [BTW87] as a simple model of self-organized criticality; much of the general, graphical theory was subsequently developed by Dhar [Dha90,Dha99]. The ASM is by now studied in many parts of both physics and pure mathematics: for instance, following the seminal work of Baker and Norine [BN07], it is known that this model is intimately related to tropical algebraic geometry (specifically, divisor theory for tropical curves [GK08,MZ08]); meanwhile, the ASM is studied by probabilists because of its remarkable scaling-limit behavior [PS13,LPS16]; and there are also interesting complexity-theoretic questions related to the ASM, such as, what is the complexity of determining whether a given configuration stabilizes [KT15,FL16]. For more on sandpiles, consult the short survey article [LP10] or the recent textbook [CP18].…”