refactor: Lint

This commit is contained in:
jstoobysmith 2025-01-11 17:11:38 +00:00
parent 6a3bb431bf
commit 4fa4a28d5d
3 changed files with 43 additions and 38 deletions

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@ -24,14 +24,16 @@ noncomputable def toSelfAdjointMap' (M : ℂ²ˣ²) : ℍ₂ →ₗ[] ℍ₂
map_smul' | r, ⟨A, _⟩ => Subtype.ext <| by simp
open Complex (I normSq) in
theorem toSelfAdjointMap_det_one' {M : ℂ²ˣ²} (hM : M.IsUpperTriangular) (detM : M.det = 1)
: LinearMap.det (toSelfAdjointMap' M) = 1 :=
lemma toSelfAdjointMap_det_one' {M : ℂ²ˣ²} (hM : M.IsUpperTriangular) (detM : M.det = 1) :
LinearMap.det (toSelfAdjointMap' M) = 1 :=
let b : Basis (Fin 2 ⊕ Fin 2) ℍ₂ := Basis.ofEquivFun {
toFun := fun ⟨A, _⟩ => ![(A 0 0).re, (A 1 1).re] ⊕ᵥ ![(A 0 1).re, (A 0 1).im]
map_add' := fun _ _ => funext fun | .inl 0 | .inl 1 | .inr 0 | .inr 1 => rfl
map_smul' := fun _ _ => funext fun | .inl 0 | .inl 1 | .inr 0 | .inr 1 => by simp
invFun := fun p => {
val := let z : := ⟨p (.inr 0), p (.inr 1)⟩ ; !![p (.inl 0), z; conj z, p (.inl 1)]
val :=
let z : := ⟨p (.inr 0), p (.inr 1)⟩
!![p (.inl 0), z; conj z, p (.inl 1)]
property := Matrix.ext fun | 0, 0 | 0, 1 | 1, 0 | 1, 1 => by simp
}
left_inv := fun ⟨A, hA⟩ => Subtype.ext <| Matrix.ext fun
@ -46,12 +48,11 @@ theorem toSelfAdjointMap_det_one' {M : ℂ²ˣ²} (hM : M.IsUpperTriangular) (de
let E₂ : ℂ²ˣ² := !![0, 1; conj 1, 0] -- b (.inr 0)
let E₃ : ℂ²ˣ² := !![0, I; conj I, 0] -- b (.inr 1)
let F : Matrix (Fin 2 ⊕ Fin 2) (Fin 2 ⊕ Fin 2) := LinearMap.toMatrix b b (toSelfAdjointMap' M)
let A := F.toBlocks₁₁ ; let B := F.toBlocks₁₂ ; let C := F.toBlocks₂₁ ; let D := F.toBlocks₂₂
let x := M 0 0 ; let y := M 1 1 ; have hM10 : M 1 0 = 0 := hM <| show 0 < 1 by decide
let A := F.toBlocks₁₁; let B := F.toBlocks₁₂; let C := F.toBlocks₂₁; let D := F.toBlocks₂₂
let x := M 0 0; let y := M 1 1; have hM10 : M 1 0 = 0 := hM <| show 0 < 1 by decide
have he : M = !![x, _; 0, y] := Matrix.ext fun | 0, 0 | 0, 1 | 1, 1 => rfl | 1, 0 => hM10
have he' : Mᴴ = !![conj x, 0; _, conj y] :=
Matrix.ext fun | 0, 0 | 1, 0 | 1, 1 => rfl | 0, 1 => by simp [hM10]
have detA_one : normSq x * normSq y = 1 := congrArg Complex.re <|
calc ↑(normSq x * normSq y)
_ = x * conj x * (y * conj y) := by simp [Complex.mul_conj]
@ -64,10 +65,10 @@ theorem toSelfAdjointMap_det_one' {M : ℂ²ˣ²} (hM : M.IsUpperTriangular) (de
_ = 1 := detM
have detD_one : D.det = 1 :=
let z := x * conj y
have k₀ : (M * E₂ * Mᴴ) 0 1 = z := by rw [he', he] ; simp [E₂]
have k₀ : (M * E₂ * Mᴴ) 0 1 = z := by rw [he', he]; simp [E₂]
have k₁ : (M * E₃ * Mᴴ) 0 1 = ⟨-z.im, z.re⟩ :=
calc
_ = x * I * conj y := by rw [he', he] ; simp [E₃]
_ = x * I * conj y := by rw [he', he]; simp [E₃]
_ = Complex.I * z := by ring
_ = ⟨-z.im, z.re⟩ := z.I_mul
have hD : D = !![z.re, -z.im; z.im, z.re] := Matrix.ext fun
@ -81,33 +82,33 @@ theorem toSelfAdjointMap_det_one' {M : ℂ²ˣ²} (hM : M.IsUpperTriangular) (de
letI : Invertible D.det := detD_one ▸ invertibleOne
letI : Invertible D := D.invertibleOfDetInvertible
have hE : A - B * ⅟D * C = !![normSq x, _; 0, normSq y] :=
have k : (M * E₀ * Mᴴ) 0 1 = 0 := by rw [he', he] ; simp [E₀]
have k : (M * E₀ * Mᴴ) 0 1 = 0 := by rw [he', he]; simp [E₀]
have hC00 : C 0 0 = 0 := congrArg Complex.re k
have hC10 : C 1 0 = 0 := congrArg Complex.im k
Matrix.ext fun
| 0, 1 => rfl
| 1, 0 =>
have hA10 : A 1 0 = 0 := congrArg Complex.re <|
show (M * E₀ * Mᴴ) 1 1 = 0 by rw [he', he] ; simp [E₀]
show (M * E₀ * Mᴴ) 1 1 = 0 by rw [he', he]; simp [E₀]
show A 1 0 - (B * ⅟D) 1 ⬝ᵥ (C · 0) = 0 by simp [hC00, hC10, hA10]
| 0, 0 =>
have hA00 : A 0 0 = normSq x := congrArg Complex.re <|
show (M * E₀ * Mᴴ) 0 0 = normSq x by rw [he', he] ; simp [E₀, x.mul_conj]
show (M * E₀ * Mᴴ) 0 0 = normSq x by rw [he', he]; simp [E₀, x.mul_conj]
show A 0 0 - (B * ⅟D) 0 ⬝ᵥ (C · 0) = normSq x by simp [hC00, hC10, hA00]
| 1, 1 =>
have hA11 : A 1 1 = normSq y := congrArg Complex.re <|
show (M * E₁ * Mᴴ) 1 1 = normSq y by rw [he', he] ; simp [E₁, y.mul_conj]
show (M * E₁ * Mᴴ) 1 1 = normSq y by rw [he', he]; simp [E₁, y.mul_conj]
have hB10 : B 1 0 = 0 := congrArg Complex.re <|
show (M * E₂ * Mᴴ) 1 1 = 0 by rw [he', he] ; simp [E₂]
show (M * E₂ * Mᴴ) 1 1 = 0 by rw [he', he]; simp [E₂]
have hB11 : B 1 1 = 0 := congrArg Complex.re <|
show (M * E₃ * Mᴴ) 1 1 = 0 by rw [he', he] ; simp [E₃]
show (M * E₃ * Mᴴ) 1 1 = 0 by rw [he', he]; simp [E₃]
calc A 1 1 - (B * ⅟D * C) 1 1
_ = A 1 1 - B 1 ⬝ᵥ ((⅟D * C) · 1) := by noncomm_ring
_ = normSq y := by simp [hB10, hB11, hA11]
calc LinearMap.det (toSelfAdjointMap' M)
_ = F.det := (LinearMap.det_toMatrix ..).symm
_ = D.det * (A - B * ⅟D * C).det := F.fromBlocks_toBlocks ▸ Matrix.det_fromBlocks₂₂ ..
_ = 1 := by rw [hE] ; simp [detD_one, detA_one]
_ = 1 := by rw [hE]; simp [detD_one, detA_one]
/-- This promotes `Lorentz.SL2C.toSelfAdjointMap M` and its definitional equivalence,
`Lorentz.SL2C.toSelfAdjointMap' M`, to a linear equivalence by recognising the linear inverse to be
@ -124,17 +125,17 @@ noncomputable def toSelfAdjointEquiv (M : ℂ²ˣ²) [Invertible M] : ℍ₂ ≃
_ = M * M⁻¹ * A * (M * M⁻¹)ᴴ := by noncomm_ring [Matrix.conjTranspose_mul]
_ = A := by simp
theorem toSelfAdjointMap_mul (M N : ℂ²ˣ²)
: toSelfAdjointMap' (M * N) = toSelfAdjointMap' M ∘ₗ toSelfAdjointMap' N :=
lemma toSelfAdjointMap_mul (M N : ℂ²ˣ²) :
toSelfAdjointMap' (M * N) = toSelfAdjointMap' M ∘ₗ toSelfAdjointMap' N :=
LinearMap.ext fun A => Subtype.ext <|
show M * N * A * (M * N)ᴴ = M * (N * A * Nᴴ) * Mᴴ by noncomm_ring [Matrix.conjTranspose_mul]
theorem toSelfAdjointMap_similar_det (M N : ℂ²ˣ²) [Invertible M]
: LinearMap.det (toSelfAdjointMap' (M * N * M⁻¹)) = LinearMap.det (toSelfAdjointMap' N) :=
lemma toSelfAdjointMap_similar_det (M N : ℂ²ˣ²) [Invertible M] :
LinearMap.det (toSelfAdjointMap' (M * N * M⁻¹)) = LinearMap.det (toSelfAdjointMap' N) :=
let e := toSelfAdjointEquiv M
let f := toSelfAdjointMap' N
suffices toSelfAdjointMap' (M * N * M⁻¹) = e ∘ₗ f ∘ₗ e.symm from this ▸ f.det_conj e
by rw [toSelfAdjointMap_mul, toSelfAdjointMap_mul] ; rfl
by rw [toSelfAdjointMap_mul, toSelfAdjointMap_mul]; rfl
end SL2C
end Lorentz