Complexity economics is a heterodox alternative to neoclassical and mainstream economics, that starts with an assumption of complex system dynamics, and attempts to model economic system behaviour from that.

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Complexity economics is the application of complexity science to the problems of economics. It relaxes several common assumptions in economics, including general equilibrium theory. While it does not reject the existence of an equilibrium, it features a non-equilibrium approach and sees such equilibria as a special case and as an emergent property resulting from complex interactions between economic agents. The complexity science approach has also been applied to computational economics.