  We propose an ODE-based derivation for a generalized class of opinion
formation models either for single and multiple species (followers, leaders,
trolls). The approach is purely deterministic and the evolution of the single
opinion is determined by the competition between two mechanisms: the opinion
diffusion and the compromise process. Such deterministic approach allows to
recover in the limit an aggregation/(nonlinear)diffusion system of PDEs for the
macroscopic opinion densities.
