Normal forms for differentiable maps near a fixed point (Q1969412)

The authors study further reduction of normal forms for differentiable maps near a fixed point. Classical methods to obtain real normal forms first compute a normal form of the complexification. Since complex eigenvalues occur in conjugate pairs, then through appropriate transformations it is possible to get a real normal form. Nevertheless the authors' approach is rational in the sense that if the coefficients of the map are in a field \(K\) (of characteristic zero), so is its normal form, and all computations are done in \(K\).