Sonja Hochloch (University of Antwerp)
Abstract: In this talk, we will explain how the goal of symplectically classifying integrable systems on 4-dimensional manifolds with underlying S^1-symmetry led to the discovery and subsequent study of a new type of bifurcation, called double flip bifurcation. We give a normal form for systems going through this bifurcation and calculate some examples.
The bifurcation part of this talk is based on the joint work arXiv:2511.12086 with K. Efstathiou (Duke Kunshan University) and Tobias Henriksen (Antwerpen & Groningen).