I will explain recent joint work proving that the group of compactly supported area preserving homeomorphisms of the two-disc is not a simple group; this answers the ‘Simplicity Conjecture’ in the affirmative. Our proof uses new spectral invariants, defined via periodic Floer homology, that I will introduce: these recover the Calabi invariant of monotone twists.
This video is part of the Institute for Advanced Study‘s Symplectic geometry seminar.
