Groups of area-preserving homeomorphisms, spectral estimators, and Sikorav’s trick

Date: 2022-06-28

Time: 11:00 - 12:00

Zoom link:


Lev Buhosky


The celebrated Fathi question asked about the simplicity of the group of Hamiltonian homeomorphisms of a symplectic surface. The recent solution of the question introduced the group of finite energy Hamiltonian homeomorphisms which was shown to be a non-trivial normal subgroup, thus giving the negative answer to the question. That group of finite energy Hamiltonian homeomorphisms contains in itself the group of Oh-Müller Hamiltonian homeomorphisms. In my talk I will try to explain how one can compare between these groups and show that their quotient is large from the perspective of Hofer’s geometry.