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Convergence on a cylindrical end from uniform convergence of loops up to phase

Proved
FiniteEnergyPlane.cylEnd_tendsto_of_loops_tendstoUnif_mod_phase

by Mazecto · Nov 1, 2026 · Mathlib 0df444a (Lean v4.33.1)

asymptotic-analysispseudoholomorphic-curvessymplectization

Let uuu be a finite-energy J~\tilde JJ~-holomorphic curve on D∖{0}D\setminus\{0\}D∖{0} (strictly star-shaped level S=H−1(1)S=H^{-1}(1)S=H−1(1), compatible JJJ), P=(x,T)P=(x,T)P=(x,T) a periodic Reeb orbit and σ=±1\sigma=\pm1σ=±1. Suppose that for every ϵ>0\epsilon>0ϵ>0 and all sufficiently small r>0r>0r>0 there is a phase c′c'c′ (depending on rrr) with ∥proj u(re−2πit)−x(σTt+c′)∥≤ϵ\|\mathrm{proj}\,u(re^{-2\pi it})-x(\sigma Tt+c')\|\le\epsilon∥proju(re−2πit)−x(σTt+c′)∥≤ϵ for all ttt. Let a(s,t)a(s,t)a(s,t) and w(s,t)w(s,t)w(s,t) be the R\mathbb{R}R- and SSS-components of u(e−2π(s+it))u(e^{-2\pi(s+it)})u(e−2π(s+it)). Then

  • aaa and www are smooth on some (s0,∞)×R(s_0,\infty)\times\mathbb{R}(s0​,∞)×R;
  • every derivative of order ≥1\ge1≥1 of a(s,t)−σTsa(s,t)-\sigma Tsa(s,t)−σTs tends to 000 uniformly in ttt as s→+∞s\to+\inftys→+∞;
  • for every mmm and ϵ>0\epsilon>0ϵ>0, for all large sss there is a phase c′c'c′ with ∥Dj(w−x(σT ⋅+c′))(s,t)∥≤ϵ\|D^j\big(w-x(\sigma T\,\cdot+c')\big)(s,t)\|\le\epsilon∥Dj(w−x(σT⋅+c′))(s,t)∥≤ϵ for all j≤mj\le mj≤m and all ttt.

Only C0C^0C0 closeness of the loops is assumed; no nondegeneracy of PPP is required.

Formalization Note The loops are loopInS H u (cwLoop 0 r); aaa, www are endA H u cylEnd, endW H u cylEnd; derivatives are iteratedFDeriv on R2\mathbb{R}^2R2.

Preamble
import Definitions.Def_FiniteEnergyPlane_Asymptotics
Formal statement
namespace FiniteEnergyPlane

open MeasureTheory Metric Filter Topology
open scoped ContDiff ENNReal Real

/-- Convergence on the cylindrical end from `C⁰` convergence of the loops up to phase. Let `u` be a
finite-energy curve on `D \ {0}` and suppose that, as `r → 0⁺`, the loops
`t ↦ proj H (u (r e^{-2πit}))` become uniformly `ε`-close to some phase shift
`t ↦ x(σTt + c')` of the Reeb orbit `P` (the phase `c'` may depend on `r`). Then `a = endA` and
`w = endW` are smooth on some `(s₀, ∞) × ℝ`, all derivatives of order `≥ 1` of `a(s, t) - σTs`
tend to `0` uniformly, and for every `m` and `ε > 0`, for all large `s` there is a phase `c'`
with `D^j (w - x(σT · + c'))(s, t)` of norm `≤ ε` for all `j ≤ m` and all `t`. -/
theorem cylEnd_tendsto_of_loops_tendstoUnif_mod_phase {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) (P : ReebOrbit H) (σ : ℝ)
    (hσ : σ = 1 ∨ σ = -1)
    (hloop : ∀ ε : ℝ, 0 < ε → ∀ᶠ r in 𝓝[>] (0 : ℝ), ∃ c' : ℝ, ∀ t : ℝ,
      ‖loopInS H u (cwLoop 0 r) t - P.x (σ * P.T * t + c')‖ ≤ ε) :
    (∃ s₀ : ℝ, ContDiffOn ℝ ∞ (endA H u cylEnd) (Set.Ioi s₀ ×ˢ Set.univ) ∧
        ContDiffOn ℝ ∞ (endW H u cylEnd) (Set.Ioi s₀ ×ˢ Set.univ)) ∧
      (∀ m : ℕ, 1 ≤ m → ∀ ε > 0, ∃ s₁ : ℝ, ∀ s ≥ s₁, ∀ t : ℝ,
        ‖iteratedFDeriv ℝ m (fun p : ℝ × ℝ => endA H u cylEnd p - σ * P.T * p.1) (s, t)‖ ≤ ε) ∧
      ∀ m : ℕ, ∀ ε > 0, ∃ s₁ : ℝ, ∀ s ≥ s₁, ∃ c' : ℝ, ∀ j ≤ m, ∀ t : ℝ,
        ‖iteratedFDeriv ℝ j
          (fun p : ℝ × ℝ => endW H u cylEnd p - P.x (σ * P.T * p.2 + c')) (s, t)‖ ≤ ε := by
  sorry

end FiniteEnergyPlane
Source
Used for U. Hryniewicz, Systems of global surfaces of section for dynamically convex Reeb flows on the 3-sphere, J. Symplectic Geom. 12 (2014), arXiv:1105.2077, Theorem 2.11 and Lemma 2.12; H. Hofer, K. Wysocki, E. Zehnder, Properties of pseudoholomorphic curves in symplectisations I: asymptotics, Ann. Inst. H. Poincaré Anal. Non Linéaire 13 (1996)

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