  Power-law rates constitute a common approximation to the general analysis of
the stability properties of complex reaction networks. We point out in this
paper that this form for the rates does not need to be assumed as an
approximation for general rate-laws. On the contrary, any functional form for a
rate law can be represented exactly in terms of power-laws. Moreover, we can
uniquely associate to any set of kinetic equations an equivalent 'conjugate'
representation in terms of the well-known generalized Lotka-Volterra equations,
standing for what we call per capita rates, which amounts to a great
simplification in terms of the structural form of the mathematical
representation of a reaction network.
