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Planes with small area outside shrinking disks escape to +∞+\infty+∞

Proved
FiniteEnergyPlane.tendsto_aCoord_atTop_of_small_area

by Mazecto · Nov 3, 2026 · Mathlib 0df444a (Lean v4.33.1)

compactnessfast-planespseudoholomorphic-curvesreeb-dynamicssymplectic-geometrysymplectization

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 and JJJ a smooth dλ0d\lambda_0dλ0​-compatible complex structure on ξ\xiξ. Let T>0T>0T>0, let γ>0\gamma>0γ>0 be smaller than every period at most TTT of a periodic Reeb orbit, and let e>0e>0e>0 and N∈RN\in\mathbb{R}N∈R. Let rk→0+r_k\to0^+rk​→0+ and let vkv_kvk​ be finite-energy J~\tilde JJ~-holomorphic planes with

  1. E(vk)≤TE(v_k)\le TE(vk​)≤T and ∫{∣z∣>rk}vk∗dλ≤γ\int_{\{|z|>r_k\}}v_k^*d\lambda\le\gamma∫{∣z∣>rk​}​vk∗​dλ≤γ;
  2. ∫∣z∣=ρvk∗λ≥e\int_{|z|=\rho}v_k^*\lambda\ge e∫∣z∣=ρ​vk∗​λ≥e for every counterclockwise circle of radius ρ>rk\rho>r_kρ>rk​;
  3. a(vk(z))≥−Na(v_k(z))\ge-Na(vk​(z))≥−N for all kkk and zzz.

Then inf⁡z∈Ka(vk(z))→+∞\inf_{z\in K}a(v_k(z))\to+\inftyinfz∈K​a(vk​(z))→+∞ for every compact K⊂C∖{0}K\subset\mathbb{C}\setminus\{0\}K⊂C∖{0}.

Formalization Note The conclusion is stated without an infimum: for every compact K∌0K\not\ni0K∋0 and every MMM, eventually M≤a(vk(z))M\le a(v_k(z))M≤a(vk​(z)) for all z∈Kz\in Kz∈K.

Preamble
import Definitions.Def_FiniteEnergyPlane_Compactness
Formal statement
namespace FiniteEnergyPlane

open MeasureTheory Metric Filter Topology
open scoped ContDiff ENNReal Real

/-- Hryniewicz (Trans. AMS 2012), Lemma 4.16. Let `T > 0` and let `0 < γ` be smaller than every
period at most `T` of a periodic Reeb orbit. Let `rₖ → 0⁺`, `e > 0` and `N`, and let `vₖ` be
finite-energy `J̃`-holomorphic planes with energy at most `T`, `dλ`-energy at most `γ` on
`{|z| > rₖ}`, action `∫_{|z| = ρ} vₖ*λ ≥ e` on every counterclockwise circle of radius `ρ > rₖ`,
and `aCoord H ∘ vₖ ≥ -N` everywhere. Then `aCoord H ∘ vₖ → +∞` uniformly on every compact subset
of `ℂ \ {0}`. -/
theorem tendsto_aCoord_atTop_of_small_area {n : ℕ} (H : V n → ℝ) (hH : IsStrictlyStarShapedLevel H)
    (J : V n → V n →L[ℝ] V n) (hJ : IsCompatibleXiStructure H J)
    (T γ e N : ℝ) (hγ : 0 < γ) (hγ₁ : ∀ Q : ReebOrbit H, Q.T ≤ T → γ < Q.T) (he : 0 < e)
    (r : ℕ → ℝ) (hr0 : ∀ k, 0 < r k) (hr : Tendsto r atTop (𝓝 0)) (v : ℕ → ℂ → V n)
    (hv : ∀ k, IsFiniteEnergyCurve H J Set.univ (v k))
    (hE : ∀ k, energy H Set.univ (v k) ≤ ENNReal.ofReal T)
    (hdl : ∀ k, dlambdaEnergy H {z | r k < ‖z‖} (v k) ≤ ENNReal.ofReal γ)
    (hact : ∀ k, ∀ ρ : ℝ, r k < ρ → e ≤ loopAction H (v k) (ccwLoop ρ))
    (hN : ∀ k z, -N ≤ aCoord H (v k z)) :
    ∀ Kc : Set ℂ, IsCompact Kc → (0 : ℂ) ∉ Kc →
      ∀ M : ℝ, ∀ᶠ k in atTop, ∀ z ∈ Kc, M ≤ aCoord H (v k z) := by
  sorry

end FiniteEnergyPlane
Source
U. Hryniewicz, Fast finite-energy planes in symplectizations and applications, Trans. Amer. Math. Soc. 364 (2012), 1859–1931, arXiv:0812.4076, Lemma 4.16
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What the Lean code literally says, in plain math · claude-opus-5-5

Read-back: FiniteEnergyPlane.tendsto_aCoord_atTop_of_small_area

Ambient notation. Fix n∈Nn \in \mathbb{N}n∈N (any value, including n=0n = 0n=0) and write Vn=R2(n+1)V_n = \mathbb{R}^{2(n+1)}Vn​=R2(n+1) with coordinates y0,…,y2n+1y_0, \dots, y_{2n+1}y0​,…,y2n+1​. Let j0j_0j0​ be the linear map with (j0v)2i=−v2i+1(j_0 v)_{2i} = -v_{2i+1}(j0​v)2i​=−v2i+1​ and (j0v)2i+1=v2i(j_0 v)_{2i+1} = v_{2i}(j0​v)2i+1​=v2i​, let ω0(u,v)=∑k(j0u)kvk=∑i(u2iv2i+1−u2i+1v2i)\omega_0(u,v) = \sum_k (j_0 u)_k v_k = \sum_i (u_{2i} v_{2i+1} - u_{2i+1} v_{2i})ω0​(u,v)=∑k​(j0​u)k​vk​=∑i​(u2i​v2i+1​−u2i+1​v2i​), and let λx(v)=12ω0(x,v)\lambda_x(v) = \tfrac12 \omega_0(x, v)λx​(v)=21​ω0​(x,v). For H:Vn→RH : V_n \to \mathbb{R}H:Vn​→R put (∇H(x))k=dHx(ek)(\nabla H(x))_k = dH_x(e_k)(∇H(x))k​=dHx​(ek​), XH=j0∇HX_H = j_0 \nabla HXH​=j0​∇H, and define the Reeb field

RH(x)=λx(XH(x))−1 XH(x),R_H(x) = \lambda_x(X_H(x))^{-1}\, X_H(x),RH​(x)=λx​(XH​(x))−1XH​(x),

with the convention 0−1=00^{-1} = 00−1=0. Write ξx={v:λx(v)=0, dHx(v)=0}\xi_x = \{ v : \lambda_x(v) = 0,\ dH_x(v) = 0 \}ξx​={v:λx​(v)=0, dHx​(v)=0} and SH={H=1}S_H = \{H = 1\}SH​={H=1}.

  • Hypothesis on HHH ("strictly star-shaped level"): HHH is C∞C^\inftyC∞; for every u≠0u \ne 0u=0 there is exactly one r>0r > 0r>0 with H(ru)=1H(ru) = 1H(ru)=1; and dHx(x)>0dH_x(x) > 0dHx​(x)>0 whenever H(x)=1H(x) = 1H(x)=1.
  • Hypothesis on JJJ ("compatible ξ\xiξ-structure"): J:Vn→End(Vn)J : V_n \to \mathrm{End}(V_n)J:Vn​→End(Vn​) is C∞C^\inftyC∞, and for every x∈SHx \in S_Hx∈SH​ and all v,w∈ξxv, w \in \xi_xv,w∈ξx​: J(x)v∈ξxJ(x)v \in \xi_xJ(x)v∈ξx​, J(x)2v=−vJ(x)^2 v = -vJ(x)2v=−v, ω0(v,J(x)v)>0\omega_0(v, J(x)v) > 0ω0​(v,J(x)v)>0 if v≠0v \ne 0v=0, and ω0(J(x)v,J(x)w)=ω0(v,w)\omega_0(J(x)v, J(x)w) = \omega_0(v,w)ω0​(J(x)v,J(x)w)=ω0​(v,w). Nothing is required of J(x)J(x)J(x) off SHS_HSH​ or outside ξx\xi_xξx​.
  • Scaling, projection and aaa-coordinate. For y∈Vny \in V_ny∈Vn​, sH(y)s_H(y)sH​(y) is some r>0r > 0r>0 with H(ry)=1H(ry) = 1H(ry)=1 if such an rrr exists (chosen by choice), and sH(y)=1s_H(y) = 1sH​(y)=1 otherwise. Put πH(y)=sH(y) y\pi_H(y) = s_H(y)\, yπH​(y)=sH​(y)y and aH(y)=−12log⁡sH(y)a_H(y) = -\tfrac12 \log s_H(y)aH​(y)=−21​logsH​(y). Since sH(y)>0s_H(y) > 0sH​(y)>0 always, y=e2aH(y)πH(y)y = e^{2a_H(y)} \pi_H(y)y=e2aH​(y)πH​(y).
  • The almost complex structure J~\tilde JJ~ on VnV_nVn​: for y∈Vny \in V_ny∈Vn​ let x=πH(y)x = \pi_H(y)x=πH​(y), r=sH(y)r = s_H(y)r=sH​(y), α(v)=r dHx(v)2 dHx(x)\alpha(v) = \frac{r\, dH_x(v)}{2\, dH_x(x)}α(v)=2dHx​(x)rdHx​(v)​, β(v)=rλx(v)\beta(v) = r \lambda_x(v)β(v)=rλx​(v), w(v)=v−2α(v) y−β(v) r−1RH(x)w(v) = v - 2\alpha(v)\, y - \beta(v)\, r^{-1} R_H(x)w(v)=v−2α(v)y−β(v)r−1RH​(x), and
J~(y)v=α(v) r−1RH(x)−2β(v) y+J(x) w(v).\tilde J(y) v = \alpha(v)\, r^{-1} R_H(x) - 2\beta(v)\, y + J(x)\, w(v).J~(y)v=α(v)r−1RH​(x)−2β(v)y+J(x)w(v).
  • Derivatives. For f:C→Ff : \mathbb{C} \to Ff:C→F, ∂sf(z)=Df(z)[1]\partial_s f(z) = Df(z)[1]∂s​f(z)=Df(z)[1] and ∂tf(z)=Df(z)[i]\partial_t f(z) = Df(z)[i]∂t​f(z)=Df(z)[i] (Fréchet derivatives over R\mathbb{R}R; equal to 000 where fff is not differentiable).
  • Energy. An admissible φ:R→R\varphi : \mathbb{R} \to \mathbb{R}φ:R→R is C∞C^\inftyC∞, monotone non-decreasing, with values in [0,1][0,1][0,1]. For u:C→Vnu : \mathbb{C} \to V_nu:C→Vn​ write a=aH∘ua = a_H \circ ua=aH​∘u, w=πH∘uw = \pi_H \circ uw=πH​∘u and
eφ(z)=φ′(a)(∂sa λw(∂tw)−∂ta λw(∂sw))+φ(a) ω0(∂sw,∂tw).e_\varphi(z) = \varphi'(a)\big(\partial_s a\, \lambda_w(\partial_t w) - \partial_t a\, \lambda_w(\partial_s w)\big) + \varphi(a)\, \omega_0(\partial_s w, \partial_t w).eφ​(z)=φ′(a)(∂s​aλw​(∂t​w)−∂t​aλw​(∂s​w))+φ(a)ω0​(∂s​w,∂t​w).

For U⊆CU \subseteq \mathbb{C}U⊆C, EH(U,u)=sup⁡φ admissible∫Umax⁡(eφ,0) dLeb∈[0,∞]E_H(U, u) = \sup_{\varphi \text{ admissible}} \int_U \max(e_\varphi, 0)\, d\mathrm{Leb} \in [0, \infty]EH​(U,u)=supφ admissible​∫U​max(eφ​,0)dLeb∈[0,∞] (negative parts of the density are cut off before integrating). The dλd\lambdadλ-energy is EHdλ(U,u)=∫Umax⁡(ω0(∂sw,∂tw),0) dLeb∈[0,∞]E^{d\lambda}_H(U,u) = \int_U \max\big(\omega_0(\partial_s w, \partial_t w), 0\big)\, d\mathrm{Leb} \in [0,\infty]EHdλ​(U,u)=∫U​max(ω0​(∂s​w,∂t​w),0)dLeb∈[0,∞].

  • Finite-energy curve on UUU: uuu is C∞C^\inftyC∞ on UUU (in the sense of smoothness on the set UUU), u(z)≠0u(z) \ne 0u(z)=0 for z∈Uz \in Uz∈U, at every z∈Uz \in Uz∈U the map uuu is differentiable and ∂su(z)+J~(u(z)) ∂tu(z)=0\partial_s u(z) + \tilde J(u(z))\, \partial_t u(z) = 0∂s​u(z)+J~(u(z))∂t​u(z)=0, and EH(U,u)<∞E_H(U,u) < \inftyEH​(U,u)<∞.
  • Reeb orbit: a map x:R→Vnx : \mathbb{R} \to V_nx:R→Vn​ and a number T>0T > 0T>0 with x(τ)∈SHx(\tau) \in S_Hx(τ)∈SH​, x′(τ)=RH(x(τ))x'(\tau) = R_H(x(\tau))x′(τ)=RH​(x(τ)) and x(τ+T)=x(τ)x(\tau + T) = x(\tau)x(τ+T)=x(τ) for all τ\tauτ. TTT is any period, not necessarily the minimal one, so multiple covers are included.
  • Loop action. For ρ∈R\rho \in \mathbb{R}ρ∈R let cρ(t)=ρ e2πitc_\rho(t) = \rho\, e^{2\pi i t}cρ​(t)=ρe2πit. The loop action of uuu along cρc_\rhocρ​ is
A(u,ρ)=∫01λℓ(t)(ℓ′(t)) dt,ℓ(t)=πH(u(cρ(t))),\mathcal{A}(u, \rho) = \int_0^1 \lambda_{\ell(t)}\big(\ell'(t)\big)\, dt, \qquad \ell(t) = \pi_H\big(u(c_\rho(t))\big),A(u,ρ)=∫01​λℓ(t)​(ℓ′(t))dt,ℓ(t)=πH​(u(cρ​(t))),

where ℓ′(t)\ell'(t)ℓ′(t) is taken as 000 at points where ℓ\ellℓ is not differentiable, and the integral is the Lebesgue interval integral (taken as 000 if the integrand is not integrable).

Statement. Let HHH be a strictly star-shaped level function and JJJ a compatible ξ\xiξ-structure as above. Let T,γ,e,N∈RT, \gamma, e, N \in \mathbb{R}T,γ,e,N∈R with γ>0\gamma > 0γ>0 and e>0e > 0e>0 (TTT and NNN are unrestricted in sign). Assume every Reeb orbit QQQ of HHH with period Q.T≤TQ.T \le TQ.T≤T satisfies γ<Q.T\gamma < Q.Tγ<Q.T. Let (rk)k∈N(r_k)_{k \in \mathbb{N}}(rk​)k∈N​ be positive reals with rk→0r_k \to 0rk​→0, and (vk)k∈N(v_k)_{k \in \mathbb{N}}(vk​)k∈N​ maps C→Vn\mathbb{C} \to V_nC→Vn​ such that, for every kkk:

  1. vkv_kvk​ is a finite-energy curve on all of C\mathbb{C}C;
  2. EH(C,vk)≤max⁡(T,0)E_H(\mathbb{C}, v_k) \le \max(T, 0)EH​(C,vk​)≤max(T,0);
  3. EHdλ({z:∣z∣>rk},vk)≤γE^{d\lambda}_H\big(\{ z : |z| > r_k \}, v_k\big) \le \gammaEHdλ​({z:∣z∣>rk​},vk​)≤γ;
  4. for every ρ>rk\rho > r_kρ>rk​, e≤A(vk,ρ)e \le \mathcal{A}(v_k, \rho)e≤A(vk​,ρ);
  5. aH(vk(z))≥−Na_H(v_k(z)) \ge -NaH​(vk​(z))≥−N for every z∈Cz \in \mathbb{C}z∈C.

Then for every compact set Kc⊆CK_c \subseteq \mathbb{C}Kc​⊆C with 0∉Kc0 \notin K_c0∈/Kc​ and every M∈RM \in \mathbb{R}M∈R there is k0k_0k0​ such that for all k≥k0k \ge k_0k≥k0​ and all z∈Kcz \in K_cz∈Kc​,

aH(vk(z))≥M.a_H\big(v_k(z)\big) \ge M.aH​(vk​(z))≥M.

Edge cases visible in the statement. Kc=∅K_c = \emptysetKc​=∅ is allowed (the conclusion is then trivial). If T<0T < 0T<0, condition 2 says EH(C,vk)=0E_H(\mathbb{C}, v_k) = 0EH​(C,vk​)=0. The hypothesis on Reeb orbits concerns only orbits with period ≤T\le T≤T; if no such orbit exists it is vacuous, and when it is not vacuous it says no Reeb orbit has period in (0,min⁡(T,γ)](0, \min(T, \gamma)](0,min(T,γ)]. Condition 4 bounds the loop action from below for every radius ρ>rk\rho > r_kρ>rk​, with the same eee for all kkk. Condition 5 is a uniform lower bound on the aaa-coordinate, with the same NNN for all kkk and zzz.

Human review
  • Endorsed by Shuze Chen · Nov 3, 2026

    Confirmed by the moderator at approval.

  • Endorsed by Mazecto · Nov 3, 2026

    Confirmed by the mission captain (proposal self-audit).

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