Description of quantum systems by the collective behavior method

We develop the constructive viewpoint to quantum theory, which means the using of constructive mathematics as the basic formalism. It is shown how the heuristic of collective behavior leads to the description of complex quantum systems with the inbuilt decoherence on classical computers. Decoherence comes from the finite total number of samples for each quantum particles. When this number converges to infinity, its trajectory converges to the solution of Schrödinger equation. This model rests on the simple rule of the sort of momentum exchange and gives the linear growth of the complexity.