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We provide a family of isolated tangent to the identity germs $f:(mathbb{C}^3,0) to (mathbb{C}^3,0)$ which possess only degenerate characteristic directions, and for which the lift of $f$ to any modification (with suitable properties) has only degenerate characteristic directions. This is in sharp contrast with the situation in dimension $2$, where any isolated tangent to the identity germ $f$ admits a modification where the lift of $f$ has a non-degenerate characteristic direction. We compare this situation with the resolution of singularities of the infinitesimal generator of $f$, showing that this phenomenon is not related to the non-existence of complex separatrices for vector fields of Gomez-Mont and Luengo. Finally, we describe the set of formal $f$-invariant curves, and the associated parabolic manifolds, using the techniques recently developed by Lopez-Hernanz, Raissy, Ribon, Sanz Sanchez, Vivas.
Let $R$ be a ring of characteristic $0$ with field of fractions $K$, and let $mge2$. The Bottcher coordinate of a power series $varphi(x)in x^m + x^{m+1}R[![x]!]$ is the unique power series $f_varphi(x)in x+x^2K[![x]!]$ satisfying $varphicirc f_varph
In many cases rational surfaces obtained by desingularization of birational dynamical systems are not relatively minimal. We propose a method to obtain coordinates of relatively minimal rational surfaces by using blowing down structure. We apply this
We prove that a hyperbolic Dulac germ with complex coefficients in its expansion is linearizable on a standard quadratic domain and that the linearizing coordinate is again a complex Dulac germ. The proof uses results about normal forms of hyperbolic transseries from another work of the authors.
We give a combinatorial criterion for a critical diameter to be compatible with a non-degenerate quadratic lamination.
We show that each of Veechs original examples of translation surfaces with ``optimal dynamics whose trace field is of degree greater than two has non-periodic directions of vanishing SAF-invariant. Furthermore, we give explicit examples of pseudo-Ano