G. Cicogna , G. Gaeta LIE-POINT SYMMETRIES AND NONLINEAR DYNAMICAL SYSTEMS (A review on symmetry and approximate symmetries of nonlinear equations: bifurcations, center manifolds, and normal form reduction) (42K, LaTeX) ABSTRACT. Nonlinear symmetries of finite dimensional dynamical systems are related to nonlinear normal forms and center manifolds in the neighbourhood of a singular point. Certain abstract results can be used algorithmically to construct the normal forms and/or the center manifold up to a given order in the perturbation expansion. We also argue that for this task, approximate symmetries are as useful as exact ones.