Special Year Seminar II

Multi-variate residues on Grassmannians $G(k,n)$ and moduli spaces $M_{0,n}$ are ubiquitous in the study of scattering amplitudes; they provide a powerful and essential tool. Amenable theories include the biadjoint scalar, NLSM, Yang-Mills, gravity and $N=4$ Super Yang-Mills and more. I will review a relation between such multi-variate residues and the real tropical Grassmannian, i.e. the set of valuated matroids which are realizable over the real numbers. In this way, a physical problem becomes a question in geometric combinatorics.