The descent conjecture for the continuous Calabi quasi-morphism on the two-sphere

Let Pham(Sympeo(S2),id){\mathcal P}^{ham}(Sympeo(S^2),id) denote the space of continuous Hamiltonian paths from the identity, let μpath\overline\mu^{path} be the extension of the homogeneous Calabi quasi-morphism, and let ev1\overline{ev}_1 be the time-one evaluation map. Fathi's conjecture. The quasi-morphism descends to a homogeneous quasi-morphism μ:Hameo(S2)R\overline\mu:Hameo(S^2)\to\mathbb R such that

μpath=μev1.\overline\mu^{path}=\overline\mu\circ\overline{ev}_1.

Equivalently, μpath(λ)\overline\mu^{path}(\lambda) depends only on the time-one map λ(1)\lambda(1) for λPham(Sympeo(S2),id)\lambda\in{\mathcal P}^{ham}(Sympeo(S^2),id). The conjecture is intended to address simplicity questions for area-preserving homeomorphisms; the corresponding smooth statement was proved by Entov and Polterovich, while the source gives no resolution for the continuous setting.

Sources & referencesView supporting material

Primary source

Yong-Geun OH, “The group of Hamiltonian homeomorphisms and continuous Hamiltonian flows”, arXiv:math/0601200 (2009).

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