Foundations of Complex-System Theories: In Economics, Evolutionary Biology, and Statistical PhysicsComplex behavior can occur in any system made up of large numbers of interacting constituents, be they atoms in a solid, cells in a living organism, or consumers in a national economy. Analysis of this behavior often involves making important assumptions and approximations, the exact nature of which vary from subject to subject. Foundations of Complex system Theories begins with a description of the general features of complexity and then examines a