OAI/GroupTheory/PolycyclicRecognition/Algebra/ComplexCharacterLift.lean
3 declarations, 0 contain sorry, 0 declared as axioms
Additive lifts of complex characters
Rotational diagonal characters in a simply connected solvable group have continuous logarithms. Uniqueness of covering lifts makes the normalized logarithm additive; its value on an exponential curve is the prescribed linear weight, with no choice of a global principal logarithm.
- theorem
OAI.PolycyclicRecognition.eq_of_continuous_complex_exp_eqline 21Source documentation
Two continuous lifts through the complex exponential agree everywhere when they agree at one point of a connected domain.
theorem eq_of_continuous_complex_exp_eq {X : Type*} [TopologicalSpace X] [PreconnectedSpace X] {f g : X → ℂ} (hf : Continuous f) (hg : Continuous g) (he : ∀ x, Complex.exp (f x) = Complex.exp (g x)) (x₀ : X) (h₀ : f x₀ = g x₀) : f = g := by … - theorem
OAI.PolycyclicRecognition.exists_additive_lift_complex_characterline 32Source documentation
A continuous character into the nonzero complex numbers has a normalized additive lift on a simply connected group.
theorem exists_additive_lift_complex_character {G : Type*} [Group G] [TopologicalSpace G] [IsTopologicalGroup G] [SimplyConnectedSpace G] [LocallyPathConnectedSpace G] (χ : G →* ℂˣ) (hχ : Continuous (fun g => (χ g : ℂ))) : ∃ π : G →* Multiplicative ℂ, Continuous (fun g => (π g).toAdd) ∧ ∀ g, Complex.exp (π g).toAdd = (χ g : ℂ) := by … - theorem
OAI.PolycyclicRecognition.additive_lift_complex_character_on_curveline 59Source documentation
The additive lift recovers the exact weight along a continuous one-parameter curve starting at the identity.
theorem additive_lift_complex_character_on_curve {G : Type*} [Group G] [TopologicalSpace G] (χ : G →* ℂˣ) (π : G →* Multiplicative ℂ) (hπ : Continuous (fun g => (π g).toAdd)) (he : ∀ g, Complex.exp (π g).toAdd = (χ g : ℂ)) (γ : ℝ → G) (hγ : Continuous γ) (hγ0 : γ 0 = 1) (z : ℂ) (hz : ∀ t, (χ (γ t) : ℂ) = Complex.exp ((t : ℂ) * z)) : ∀ t, (π (γ t)).toAdd = (t : ℂ) * z := by …