Cicogna G., Gaeta G.
Approximate symmetries in dynamical systems
(53K, TeX)

ABSTRACT.  The knowledge of exact symmetries of a differential
problem allows to reduce it, and sometimes to completely solve it;
it also allows to obtain exact solutions. If we are looking for
approximate rather than exact solutions, then approximate symmetries are
as good as exact ones; moreover, they can be determined
perturbatively. In this paper we introduce and study approximate
symmetries, together with some applications to the determination of
approximate solutions of dynamical systems.