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K\"ahler complexity one Hamiltonian $T$-manifolds have trivial paintings

Symplectic Geometry 2026-03-16 v1 Differential Geometry

Abstract

Let a torus TT act on a symplectic manifold (M,ω)(M,\omega) with moment map ϕ\phi. We say that the Hamiltonian TT-manifold (M,ω,ϕ)(M,\omega,\phi) has complexity one if 12dimMdimT=1\frac{1}{2} \dim M - \dim T = 1, and that it is K\"ahler if it admits an invariant compatible complex structure. In this paper, we show how the class of K\"ahler complexity one Hamiltonian TT-manifolds sits inside the class of complexity one Hamiltonian TT-manifolds by proving that every compact, connected K\"ahler complexity one Hamiltonian TT-manifold has a trivial painting. As a corollary, we show that two tall compact, connected K\"ahler complexity one Hamiltonian TT-manifolds are symplectomorphic exactly if they have the same genus, Duistermaat-Heckman measure, and skeleton. Here, (M,ω,ϕ)(M,\omega,\phi) is tall exactly if every non-empty fiber ϕ1(α)\phi^{-1}(\alpha) contains more than one orbit.

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Cite

@article{arxiv.2603.12404,
  title  = {K\"ahler complexity one Hamiltonian $T$-manifolds have trivial paintings},
  author = {Isabelle Charton and Liat Kessler and Susan Tolman},
  journal= {arXiv preprint arXiv:2603.12404},
  year   = {2026}
}

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15 pages