$C^0$-rigidity of the Hamiltonian diffeomorphism group of symplectic rational surfaces

Fuente: arXiv
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Autores principales: Atallah, Marcelo, Mak, Cheuk Yu, Wu, Weiwei
Formato: Preprint
Publicado: 2025
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author Atallah, Marcelo
Mak, Cheuk Yu
Wu, Weiwei
author_facet Atallah, Marcelo
Mak, Cheuk Yu
Wu, Weiwei
contents We investigate the $C^0$-topology of the group of symplectic diffeomorphisms of positive symplectic rational surfaces. For all but a few exceptions, we prove that the group of Hamiltonian diffeomorphisms forms a connected component in the $C^0$-topology. This provides the first nontrivial case in which the group of Hamiltonian diffeomorphisms is known to be $C^0$-closed inside the group of symplectic diffeomorphisms. The key to our approach is to build a bridge between techniques from symplectic mapping class groups and problems in $C^0$-symplectic topology. Via a careful adaptation of tools from $J$-holomorphic foliation and inflation, we establish the necessary $C^0$-distance estimates. We hope that this serves as an example of how these two subfields can interact fruitfully, and also propose several questions arising from this interplay.
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id arxiv_https___arxiv_org_abs_2508_20285
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle $C^0$-rigidity of the Hamiltonian diffeomorphism group of symplectic rational surfaces
Atallah, Marcelo
Mak, Cheuk Yu
Wu, Weiwei
Symplectic Geometry
Geometric Topology
We investigate the $C^0$-topology of the group of symplectic diffeomorphisms of positive symplectic rational surfaces. For all but a few exceptions, we prove that the group of Hamiltonian diffeomorphisms forms a connected component in the $C^0$-topology. This provides the first nontrivial case in which the group of Hamiltonian diffeomorphisms is known to be $C^0$-closed inside the group of symplectic diffeomorphisms. The key to our approach is to build a bridge between techniques from symplectic mapping class groups and problems in $C^0$-symplectic topology. Via a careful adaptation of tools from $J$-holomorphic foliation and inflation, we establish the necessary $C^0$-distance estimates. We hope that this serves as an example of how these two subfields can interact fruitfully, and also propose several questions arising from this interplay.
title $C^0$-rigidity of the Hamiltonian diffeomorphism group of symplectic rational surfaces
topic Symplectic Geometry
Geometric Topology
url https://arxiv.org/abs/2508.20285