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A puncture with bounded symplectization coordinate is removable

Proved
FiniteEnergyPlane.isRemovablePuncture_of_abs_aCoord_le

by Mazecto · Oct 26, 2026 · Mathlib 0df444a (Lean v4.33.1)

finite-energypseudoholomorphic-curvessymplectic-geometry

Let S=H−1(1)⊂R2n+2S=H^{-1}(1)\subset\mathbb R^{2n+2}S=H−1(1)⊂R2n+2 be a strictly star-shaped level with contact form λ=λ0∣S\lambda=\lambda_0|_Sλ=λ0​∣S​ and dλd\lambdadλ-compatible complex structure JJJ on ξ\xiξ, and let u=(a,w):D˙=D∖{0}→R×S≅R2n+2∖{0}u=(a,w):\dot D=D\setminus\{0\}\to\mathbb R\times S\cong\mathbb R^{2n+2}\setminus\{0\}u=(a,w):D˙=D∖{0}→R×S≅R2n+2∖{0} be a finite-energy J~\tilde JJ~-holomorphic curve on the punctured unit disc. If a∘ua\circ ua∘u is bounded on some punctured neighbourhood 0<∣z∣<r0<|z|<r0<∣z∣<r of the puncture, then the puncture is removable: uuu agrees on D˙\dot DD˙ with a smooth J~\tilde JJ~-holomorphic map D→R2n+2∖{0}D\to\mathbb R^{2n+2}\setminus\{0\}D→R2n+2∖{0}.

This is the bounded case of the asymptotic description of finite-energy punctured discs: a puncture that is not removable must send aaa to ±∞\pm\infty±∞ along some sequence. No gradient bound or charge condition is assumed.

Formalization Note R×S\mathbb R\times SR×S is identified with R2n+2∖{0}\mathbb R^{2n+2}\setminus\{0\}R2n+2∖{0} by (a,x)↦e2ax(a,x)\mapsto e^{2a}x(a,x)↦e2ax, and aaa is aCoord H. Finite energy is Hofer's energy energy H, as in IsFiniteEnergyCurve. Removability is IsRemovablePuncture H J u 0 1.

Preamble
import Definitions.Def_FiniteEnergyPlane_Setting
Formal statement
namespace FiniteEnergyPlane

open MeasureTheory Metric Filter Topology
open scoped ContDiff ENNReal Real

/-- A puncture near which the symplectization coordinate `a` stays bounded is removable. -/
theorem isRemovablePuncture_of_abs_aCoord_le {n : ℕ} (H : V n → ℝ)
    (hH : IsStrictlyStarShapedLevel H) (J : V n → V n →L[ℝ] V n)
    (hJ : IsCompatibleXiStructure H J) (u : ℂ → V n)
    (hu : IsFiniteEnergyCurve H J (ball 0 1 \ {0}) u)
    (hA : ∃ r : ℝ, 0 < r ∧ ∃ A : ℝ, ∀ z : ℂ, z ≠ 0 → ‖z‖ < r → |aCoord H (u z)| ≤ A) :
    IsRemovablePuncture H J u 0 1 := by
  sorry

end FiniteEnergyPlane
Source
C. Wendl, Lectures on Symplectic Field Theory, arXiv:1612.01009, Section 9.2 (the case of a bounded curve near the puncture); H. Hofer, Invent. Math. 114 (1993), Section 3

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