This lecture contextualizes reaction-diffusion systems (RD) in a wider framework of complexity. It is shown how the concept of complexity can be founded as a precisely defined and quantifiable framework, which additionally overcomes the  usual reductionist definitions. Instead, an Aristotelian position is taken by proposing five necessary and sufficient conditions (“elements”) for complexity. It turns out that the concept of “complexity” is in a theory-model relation to RD systems. As such complexity is clearly distinguished from self-organization or (strong) emergence, concepts which apply
to RD systems, which however are not itself an instance of “complexity”yet. The most important qualities of RD systems concern their ability to create structured randomness, their creative power, and the fact that descriptional categories can NOT be mutually applied the levels before and after the emergence. The second part of the lecture introduces the linkage between various growth patterns in nature and RD systems, and gives a hint how to transfer both, complexity and a kind of abstract growth models into architecture.

complexity&growth