Schwarz–Pick, Lipschitz form to Weyl's lemma for \bar∂

TheoremSchwarz–Pick, Lipschitz form#

A holomorphic self-map of the unit disc is a nonexpanding map of the metric space TauCeti.PoincareDisc.

Together with TauCeti.PoincareDisc.isometry_iff_exists_eq_unitDiscStandardAutomorphismIsometryEquiv this says that a holomorphic self-map of the Poincaré disc is nonexpanding, and is an isometry precisely when it is a disc automorphism.

TauCeti.PoincareDisc.lipschitzWith_one {F : TauCeti.PoincareDisc → TauCeti.PoincareDisc} {f : ℂ → ℂ}
  (hf : DifferentiableOn ℂ f (Metric.ball 0 1))
  (hrep :
    ∀ (z : TauCeti.PoincareDisc),
      ↑(TauCeti.PoincareDisc.toUnitDisc (F z)) = f ↑(TauCeti.PoincareDisc.toUnitDisc z)) :
  LipschitzWith 1 F
Lean

Formalized in Tau Ceti as TauCeti.PoincareDisc.lipschitzWith_one.

Other forms

Schwarz--Pick for the Poincaré length. Formalized in Tau Ceti as TauCeti.hyperbolicLength_comp_le.

TauCeti.hyperbolicLength_comp_le {γ γ' : ℝ → ℂ} {a b : ℝ} {f : ℂ → ℂ}
  (hf : DifferentiableOn ℂ f (Metric.ball 0 1))
  (hmaps : Set.MapsTo f (Metric.ball 0 1) (Metric.ball 0 1)) (hγ : ContinuousOn γ (Set.uIcc a b))
  (hderiv : ∀ t ∈ Set.uIoo a b, HasDerivAt γ (γ' t) t) (hγ' : ContinuousOn γ' (Set.uIcc a b))
  (hmem : ∀ t ∈ Set.uIcc a b, ‖γ t‖ < 1) :
  TauCeti.hyperbolicLength (f ∘ γ) a b ≤ TauCeti.hyperbolicLength γ a b

Schwarz--Pick, distance form. Formalized in Tau Ceti as TauCeti.hyperbolicDist_map_le.

TauCeti.hyperbolicDist_map_le {f : ℂ → ℂ} (hf : DifferentiableOn ℂ f (Metric.ball 0 1))
  (hmaps : Set.MapsTo f (Metric.ball 0 1) (Metric.ball 0 1)) {z w : ℂ} (hz : z ∈ Metric.ball 0 1)
  (hw : w ∈ Metric.ball 0 1) : TauCeti.hyperbolicDist (f z) (f w) ≤ TauCeti.hyperbolicDist z w

Schwarz–Pick for the Poincaré metric. Formalized in Tau Ceti as TauCeti.PoincareDisc.dist_map_le.

TauCeti.PoincareDisc.dist_map_le {F : TauCeti.PoincareDisc → TauCeti.PoincareDisc} {f : ℂ → ℂ}
  (hf : DifferentiableOn ℂ f (Metric.ball 0 1))
  (hrep :
    ∀ (z : TauCeti.PoincareDisc),
      ↑(TauCeti.PoincareDisc.toUnitDisc (F z)) = f ↑(TauCeti.PoincareDisc.toUnitDisc z))
  (z w : TauCeti.PoincareDisc) : dist (F z) (F w) ≤ dist z w
Sources
Uses 2

TheoremShimizu's inequality at two cusps#

Let D and D' be normalized cusp data of a discrete Γ ≤ PSL(2, ℝ). If g ∈ Γ does not carry the cusp of D' to the cusp of D, then the height of g • z above the cusp of D and the height of z above the cusp of D', each measured in the scaling coordinate of its datum, have product at most D.width * D'.width.

This is Shimizu's lemma (Subgroup.im_smul_mul_im_le_abs_mul_of_upperRightHom_mem) for the conjugate group σ Γ σ⁻¹, which contains the translation by D.width, applied to σ g σ'⁻¹, which conjugates the translation by D'.width into it.

TauCeti.Subgroup.CuspDatum.im_scaling_smul_smul_mul_im_scaling_smul_le
  {Γ : Subgroup (Matrix.ProjectiveSpecialLinearGroup (Fin 2) ℝ)} (D : Γ.CuspDatum)
  [DiscreteTopology ↥Γ] (D' : Γ.CuspDatum) {g : ↥Γ} (hg : g • D'.cusp ≠ D.cusp)
  (z : UpperHalfPlane) : (D.scaling • g • z).im * (D'.scaling • z).im ≤ D.width * D'.width
Uses 1 · Used by 7

TheoremThe Stieltjes--Perron vanishing theorem#

A Nevanlinna measure gives no mass to a compact interval over which the imaginary part of the represented function is continuous up to the real axis and vanishes there. Continuity is asked for on the closed rectangle of any positive height d over the interval, as a function holomorphic near the interval supplies it.

TauCeti.measure_Icc_eq_zero_of_eq_nevanlinnaKernel_add {F : ℂ → ℂ} {mu : MeasureTheory.Measure ℝ}
  {beta c : ℝ} [MeasureTheory.IsFiniteMeasure mu]
  (hrep :
    ∀ z ∈ UpperHalfPlane.upperHalfPlaneSet,
      F z = ↑beta * z + ∫ (x : ℝ), TauCeti.nevanlinnaKernel z x ∂mu + ↑c)
  {a b d : ℝ} (hab : a < b) (hd : 0 < d)
  (hcont : ContinuousOn (fun z => (F z).im) (Set.Icc a b ×ℂ Set.Icc 0 d))
  (hzero : ∀ u ∈ Set.Icc a b, (F ↑u).im = 0) : mu (Set.Icc a b) = 0
Uses 1

TheoremUniqueness in the Riemann mapping theorem, up to a disc automorphism#

If f and g are holomorphic injections from an open set U onto the open unit disc, then there are u on the unit circle and a in the unit disc such that

g z = u * (f z - a) / (1 - conj a * f z)

for every z ∈ U.

TauCeti.exists_eqOn_unitDiscStandardAutomorphismFormula_comp {U : Set ℂ} (hU : IsOpen U)
  {f g : ℂ → ℂ} (hf : DifferentiableOn ℂ f U) (hg : DifferentiableOn ℂ g U) (hfi : Set.InjOn f U)
  (hgi : Set.InjOn g U) (hfimage : f '' U = Metric.ball 0 1) (hgimage : g '' U = Metric.ball 0 1) :
  ∃ u a, Set.EqOn g (fun z => ↑u * ((f z - ↑a) / (1 - (starRingEnd ℂ) ↑a * f z))) U
Uses 1 · Used by 1

TheoremWeyl's lemma for \bar∂#

A distributional solution with finite-dimensional complex coefficients agrees almost everywhere on its domain with a holomorphic function.

TauCeti.HasWeakConjWirtingerDerivOn.exists_differentiableOn_ae_eq.{u_1} {F : Type u_1}
  [NormedAddCommGroup F] [NormedSpace ℂ F] {μ : MeasureTheory.Measure ℂ}
  {Ω : TopologicalSpace.Opens ℂ} {u : ℂ → F} [FiniteDimensional ℂ F] [μ.IsAddHaarMeasure]
  (h : TauCeti.HasWeakConjWirtingerDerivOn μ Ω u 0) :
  ∃ v, DifferentiableOn ℂ v ↑Ω ∧ u =ᵐ[μ.restrict ↑Ω] v
Uses 1

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