An interaction system has a finite set of agents that interact pairwise, depending on the current state of the system. Symmetric decomposition of the matrix of interaction coefficients yields the representation of states by self-adjoint matrices and hence a spectral representation. As a result,...

Let N = {1,..., n} be a finite set of players and KN the complete graph on the node set N "union" {0}. Assume that the edges of KN have nonnegative weights and associate with each coalition S "subset of" N of players as cost c(S) the weight of a minimal spanning tree on the node set S "union"...