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Annulus energy between level-separated circles is bounded by the loop actions

Proved
FiniteEnergyPlane.lintegral_energyDensity_annulus_le_loopAction

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. For a level A∈RA\in\mathbb RA∈R let φA(s)=χ(s−A)2\varphi_A(s)=\chi(s-A)^2φA​(s)=χ(s−A)2, where χ\chiχ is Mathlib's smooth transition function (χ=0\chi=0χ=0 on (−∞,0](-\infty,0](−∞,0], χ=1\chi=1χ=1 on [1,∞)[1,\infty)[1,∞)), so φA\varphi_AφA​ is an admissible function in Hofer's energy. Let 0<ρ2<ρ1<10<\rho_2<\rho_1<10<ρ2​<ρ1​<1, and suppose that on each circle ∣z∣=ρi|z|=\rho_i∣z∣=ρi​ either a∘u≤Aa\circ u\le Aa∘u≤A everywhere or a∘u≥A+1a\circ u\ge A+1a∘u≥A+1 everywhere. Then

∫ρ2≤∣z∣<ρ1u∗d(φA(a)λ)  ≤  ∣Q(ρ1)∣+∣Q(ρ2)∣,\int_{\rho_2\le|z|<\rho_1} u^*d(\varphi_A(a)\lambda)\;\le\;|Q(\rho_1)|+|Q(\rho_2)|,∫ρ2​≤∣z∣<ρ1​​u∗d(φA​(a)λ)≤∣Q(ρ1​)∣+∣Q(ρ2​)∣,

where Q(ρ)=∫01w(γρ(t))∗λQ(\rho)=\int_0^1 w(\gamma_\rho(t))^*\lambdaQ(ρ)=∫01​w(γρ​(t))∗λ is the action of the clockwise loop γρ(t)=ρe−2πit\gamma_\rho(t)=\rho e^{-2\pi i t}γρ​(t)=ρe−2πit.

In words: the Hofer-energy integrand at level AAA over an annulus whose boundary circles avoid the slab A<a<A+1A<a<A+1A<a<A+1 is controlled by the actions of the two boundary loops. This is a step in the zero-charge case of the asymptotic description of finite-energy punctured discs (Hofer; Wendl, Theorem 9.8).

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. The integrand of u∗d(φ(a)λ)u^*d(\varphi(a)\lambda)u∗d(φ(a)λ) with respect to ds∧dtds\wedge dtds∧dt is energyDensity H φ u; the integral is the lower Lebesgue integral of its positive part over ball 0 ρ₁ \ ball 0 ρ₂, and Q(ρ)Q(\rho)Q(ρ) is loopAction H u (cwLoop 0 ρ).

Preamble
import Definitions.Def_FiniteEnergyPlane_Setting
import Mathlib.Analysis.SpecialFunctions.SmoothTransition
Formal statement
namespace FiniteEnergyPlane

open MeasureTheory Metric Filter Topology
open scoped ContDiff ENNReal Real

/-- Annulus energy between level-separated circles is bounded by the loop actions. Let
`φ_A(s) = smoothTransition(s - A)²` (`0` for `s ≤ A`, `1` for `s ≥ A + 1`), and let
`0 < ρ₂ < ρ₁ < 1` be radii such that on each of the two circles `‖z‖ = ρᵢ` the coordinate
`a = aCoord ∘ u` stays either `≤ A` or `≥ A + 1`. Then the integral of the energy density
`u*d(φ_A(a) λ)` over the annulus `ρ₂ ≤ ‖z‖ < ρ₁` is at most `|Q(ρ₁)| + |Q(ρ₂)|`, where `Q` is the
action of the clockwise loop. -/
theorem lintegral_energyDensity_annulus_le_loopAction {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) (A ρ₁ ρ₂ : ℝ) (h₂ : 0 < ρ₂)
    (h₂₁ : ρ₂ < ρ₁) (h₁ : ρ₁ < 1)
    (hc₁ : (∀ z : ℂ, ‖z‖ = ρ₁ → aCoord H (u z) ≤ A) ∨
      (∀ z : ℂ, ‖z‖ = ρ₁ → A + 1 ≤ aCoord H (u z)))
    (hc₂ : (∀ z : ℂ, ‖z‖ = ρ₂ → aCoord H (u z) ≤ A) ∨
      (∀ z : ℂ, ‖z‖ = ρ₂ → A + 1 ≤ aCoord H (u z))) :
    ∫⁻ z in ball 0 ρ₁ \ ball 0 ρ₂,
        ENNReal.ofReal (energyDensity H (fun s => Real.smoothTransition (s - A) ^ 2) u z) ≤
      ENNReal.ofReal (|loopAction H u (cwLoop 0 ρ₁)| + |loopAction H u (cwLoop 0 ρ₂)|) := by
  sorry

end FiniteEnergyPlane
Source
H. Hofer, Pseudoholomorphic curves in symplectizations with applications to the Weinstein conjecture in dimension three, Invent. Math. 114 (1993), 515-563, Section 3; C. Wendl, Lectures on Symplectic Field Theory, arXiv:1612.01009, Lemmas 9.14 and 9.17

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