  Time evolution equations for dynamical systems can often be derived from
generating functionals. Examples are Newton's equations of motion in classical
dynamics which can be generated within the Lagrange or the Hamiltonian
formalism. We propose that generating functionals for self-organizing complex
systems offer several advantages. Generating functionals allow to formulate
complex dynamical systems systematically and the results obtained are typically
valid for classes of complex systems, as defined by the type of their
respective generating functionals. The generated dynamical systems tend, in
addition, to be minimal, containing only few free and undetermined parameters.
We point out that two or more generating functionals may be used to define a
complex system and that multiple generating function may not, and should not,
be combined into a single overall objective function. We provide and discuss
examples in terms of adapting neural networks.
