Différences

Ci-dessous, les différences entre deux révisions de la page.

--- symplectic [2025/11/03 22:57] – g.m
+++ symplectic [2026/03/01 19:27] (Version actuelle) – g.m
@@ Ligne 1: / Ligne 1: @@
 ===== GeNeSys: Geneva-Neuchâtel Symplectic geometry seminar =====
+**2026, March 3, Tuesday, Université de Genève**, the seminar room on the 8th floor.
+h30 Marcelo Alves (Augsburg) "Polytopes and C^0-Riemannian metrics
+with positive topological entropy".
+Abstract: The topological entropy of geodesic flows has been extensively studied since the foundational works of Dinaburg and Manning. It measures the exponential complexity of the geodesic flow of a Riemannian
+manifold, and there are several results connecting it to the geometry and topology of a Riemannian manifold. In this talk I will explain how recent advances in symplectic dynamics can be used to give a meaningful extension of the topological entropy to C^0-Riemannian metrics; i.e. Riemannian metrics which are continuous but not necessarily differentiable. Similarly, using contact geometry we will explain how we
+can talk in a meaningful way about the topological entropy of convex and starshaped polytopes in R^4, thinking of them as a C^0-contact form. This is joint work with Matthias Meiwes.
+h Stepan Orevkov (Toulouse) "On curves of degree 10 with 12 triple
+points".
+Abstract. We construct an irreducible rational curve of degree 10 in CP^2 which has 12 triple points, and a union of three rational quartics with 19 triple points. This gives counter-examples to a conjecture by Dimca, Harbourne, and Sticlaru. We also prove that there exists an analytic family $C_u$ of curves of degree 10 with 12 triple points which tends as $u \to 0$ to the union of the dual Hesse
+arrangement of lines (9 lines with 12 triple points) with an additional line. We hope that our
+approach to the proof of the latter fact could be of independent interest.
 **2025, Nov 11, Tuesday, Université de Neuchâtel**