Inner geometry of complex surfaces and Laplacian formula
Given a complex analytic germ (X, 0) \subset ( C^n, 0), the standard Hermitian metric of C^n induces a natural arc-length metric on (X, 0), called the inner metric.
We study the inner metric structure of the germ of an isolated complex surface singularity (X,0) by means of a family of natural numerical invariants, called inner rates.
I will explain how these inner rates can be computed from the data consisting of the topology of (X,0), together with the configuration of a generic hyperplane section and of the polar curve of a generic plane projection of (X,0). Then I will explain some applications of this formula. In particular, I will show that this gives a first approach to the question of Lê Dung Tràng on the existence of a duality between the two algorithm of resolution of surface singularities, on one hand by a sequence of normalised blow-ups of points, and on the other hand by a sequence of normalised Nash transform. This is a joint work with André Belotto Da Silva and Lorenzo Fantini.