G. Cicogna, G. Gaeta
Nonlinear symmetries and normal forms
(375K, PS)

ABSTRACT.  We provide a unified treatment -- including some new results and 
improvement of old ones -- of normal form theory of dynamical systems 
(or vector fields) for what regards its symmetry properties under 
nonlinear transformations (Lie point-symmetries). 
We also briefly discuss the problem of the convergence of the 
normalizing transformations in the presence of symmetries.