Complexity Theory

•        It may refer to Computational Complexity Theory a field in theoretical computer science and mathematics.

       It is a branch of the theory of computation in theoretical computer science and mathematics that focuses on classifying computational problems according to their inherent difficulty. In this context, a computational problem is understood to be a task that is in principle amenable to being solved by a computer (which basically means that the problem can be stated by a set of mathematical instructions). Informally, a computational problem consists of problem instances and solutions to these problem instances. For example, primality testing is the problem of determining whether a given number is prime or not. The instances of this problem are natural numbers, and the solution to an instance is yes or no based on whether the number is prime or not.

•        The study of complex systems

• Complexity theory and organizations, the application of complexity theory to strategy

                Complexity theory has been used extensively in the field of strategic management and organizational studies. It is used in these domains to understand how organizations or firms adapt to their environments. The theory treats organizations and firms as collections of strategies and structures. When the organization or firm shares the properties of other complex adaptive systems - which is often defined as consisting of a small number of relatively simple and partially connected structures - they are more likely to adapt to their environment and, thus, survive. Complexity-theoretic thinking has been present in strategy and organizational studies since their inception as academic disciplines.

• Complexity economics, the application of complexity theory to economics

                   Complexity economics is the application of complexity science to the problems of economics. It is one of the four C's of a new paradigm surfacing in the field of economics. The four C's are complexity, chaos, catastrophe and cybernetics. This new mode of economic thought rejects traditional assumptions that imply that the economy is a closed system that eventually reaches an equilibrium. Instead, it views economies as open complex adaptive systems with endogenous evolution . Complex systems do not necessarily settle to equilibrium — even ideal deterministic models may exhibit chaos, which is distinct from both random (nondeterministic) and analytic behavior.