Montel's theorem #
A family of holomorphic maps which is bounded uniformly on each compact subset of its domain is equicontinuous. For finite-dimensional targets it has compact closure in the compact-open topology. Compactness is supplied by Mathlib's Arzelà–Ascoli theorem.
theorem
CarlsonFunctions.SeveralComplexVariables.equicontinuous_of_holomorphic_bounded_on_compacts
{ι : Type u_1}
{F : Type u_2}
[Fintype ι]
[NormedAddCommGroup F]
[NormedSpace ℂ F]
{U : TopologicalSpace.Opens (ι → ℂ)}
{S : Set (HolomorphicMap U F)}
(hb : ∀ K ⊆ ↑U, IsCompact K → ∃ (M : ℝ), ∀ f ∈ S, ∀ z ∈ K, ‖openExtension U (↑f) z‖ ≤ M)
:
Equicontinuous fun (f : ↑S) => ⇑↑↑f
Compact-local bounds on a holomorphic family give equicontinuity. Banach targets are allowed here; finite dimensionality is needed only for compactness in Montel's theorem.
theorem
CarlsonFunctions.SeveralComplexVariables.isCompact_closure_of_holomorphic_bounded_on_compacts
{ι : Type u_1}
{F : Type u_2}
[Fintype ι]
[NormedAddCommGroup F]
[NormedSpace ℂ F]
[CompleteSpace F]
[FiniteDimensional ℂ F]
{U : TopologicalSpace.Opens (ι → ℂ)}
{S : Set (HolomorphicMap U F)}
(hb : ∀ K ⊆ ↑U, IsCompact K → ∃ (M : ℝ), ∀ f ∈ S, ∀ z ∈ K, ‖openExtension U (↑f) z‖ ≤ M)
:
Montel's theorem. A compact-locally bounded family of holomorphic maps into a finite-dimensional complex normed space has compact closure in the compact-open topology.