DibyashanuPati/PhysLean
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

feat: Doing tensors generally

Browse source
This commit is contained in:
jstoobysmith 2024-07-25 16:57:57 -04:00
parent 23e041295f
commit 0f4092e0ec
11 changed files with 1408 additions and 1479 deletions
Download patch file Download diff file Expand all files Collapse all files

743
HepLean/SpaceTime/LorentzTensor/Real/Basic.lean
View file

@ -14,6 +14,8 @@ import Mathlib.Algebra.Module.Equiv
import Mathlib.Algebra.Module.LinearMap.Basic
import Mathlib.LinearAlgebra.TensorProduct.Basic
import Mathlib.LinearAlgebra.TensorProduct.Basis
import Mathlib.LinearAlgebra.PiTensorProduct
import HepLean.Mathematics.PiTensorProduct
/-!
# Real Lorentz Tensors
@ -28,59 +30,106 @@ This will relation should be made explicit in the future.
-- For modular operads see: [Raynor][raynor2021graphical]
-/
/-! TODO: Do complex tensors, with Van der Waerden notation for fermions. -/
/-! TODO: Relate the constructions here to `PiTensorProduct`. -/
/-! TODO: Generalize to maps into Lorentz tensors. -/
/-- The possible `colors` of an index for a RealLorentzTensor.
section PiTensorProductResults
variable {ι ι₂ ι₃ : Type*}
variable {R : Type*} [CommSemiring R]
variable {R₁ R₂ : Type*}
variable {s : ι → Type*} [∀ i, AddCommMonoid (s i)] [∀ i, Module R (s i)]
variable {M : Type*} [AddCommMonoid M] [Module R M]
variable {E : Type*} [AddCommMonoid E] [Module R E]
variable {F : Type*} [AddCommMonoid F]
end PiTensorProductResults
open TensorProduct
noncomputable section
/-- The possible `color` of an index for a RealLorentzTensor.
There are two possiblities, `up` and `down`. -/
inductive RealLorentzTensor.Colors where
| up : RealLorentzTensor.Colors
| down : RealLorentzTensor.Colors
inductive RealLorentzTensor.Color where
| up : RealLorentzTensor.Color
| down : RealLorentzTensor.Color
/-- The association of colors with indices. For up and down this is `Fin 1 ⊕ Fin d`. -/
def RealLorentzTensor.ColorsIndex (d : ℕ) (μ : RealLorentzTensor.Colors) : Type :=
/-- To set of allowed index values associated to a color of index. -/
def RealLorentzTensor.ColorIndex (d : ℕ) (μ : RealLorentzTensor.Color) : Type :=
match μ with
| RealLorentzTensor.Colors.up => Fin 1 ⊕ Fin d
| RealLorentzTensor.Colors.down => Fin 1 ⊕ Fin d
| RealLorentzTensor.Color.up => Fin 1 ⊕ Fin d
| RealLorentzTensor.Color.down => Fin 1 ⊕ Fin d
instance (d : ℕ) (μ : RealLorentzTensor.Colors) : Fintype (RealLorentzTensor.ColorsIndex d μ) :=
/-- The instance of a finite type on the set of allowed index values for a given color. -/
instance (d : ℕ) (μ : RealLorentzTensor.Color) : Fintype (RealLorentzTensor.ColorIndex d μ) :=
match μ with
| RealLorentzTensor.Colors.up => instFintypeSum (Fin 1) (Fin d)
| RealLorentzTensor.Colors.down => instFintypeSum (Fin 1) (Fin d)
| RealLorentzTensor.Color.up => instFintypeSum (Fin 1) (Fin d)
| RealLorentzTensor.Color.down => instFintypeSum (Fin 1) (Fin d)
instance (d : ℕ) (μ : RealLorentzTensor.Colors) : DecidableEq (RealLorentzTensor.ColorsIndex d μ) :=
/-- The color index set for each color has a decidable equality. -/
instance (d : ℕ) (μ : RealLorentzTensor.Color) : DecidableEq (RealLorentzTensor.ColorIndex d μ) :=
match μ with
| RealLorentzTensor.Colors.up => instDecidableEqSum
| RealLorentzTensor.Colors.down => instDecidableEqSum
| RealLorentzTensor.Color.up => instDecidableEqSum
| RealLorentzTensor.Color.down => instDecidableEqSum
def RealLorentzTensor.ColorModule (d : ℕ) (μ : RealLorentzTensor.Color) : Type :=
RealLorentzTensor.ColorIndex d μ → ℝ
instance (d : ℕ) (μ : RealLorentzTensor.Color) :
AddCommMonoid (RealLorentzTensor.ColorModule d μ) :=
Pi.addCommMonoid
instance (d : ℕ) (μ : RealLorentzTensor.Color) : Module ℝ (RealLorentzTensor.ColorModule d μ) :=
Pi.module _ _ _
instance (d : ℕ) (μ : RealLorentzTensor.Color) : AddCommGroup (RealLorentzTensor.ColorModule d μ) :=
Pi.addCommGroup
/-- Real Lorentz tensors. -/
def RealLorentzTensor {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Color) : Type :=
⨂[ℝ] i : X, RealLorentzTensor.ColorModule d (c i)
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Color) :
AddCommMonoid (RealLorentzTensor d c) :=
PiTensorProduct.instAddCommMonoid fun i => RealLorentzTensor.ColorModule d (c i)
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Color) :
Module ℝ (RealLorentzTensor d c) := PiTensorProduct.instModule
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Color) :
AddCommGroup (RealLorentzTensor d c) := PiTensorProduct.instAddCommGroup
namespace RealLorentzTensor
variable {d : ℕ} {X Y Z : Type} (c : X → Color)
[Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y] [Fintype Z] [DecidableEq Z]
/-- An `IndexValue` is a set of actual values an index can take. e.g. for a
3-tensor (0, 1, 2). -/
def RealLorentzTensor.IndexValue {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Colors) :
Type 0 := (x : X) → RealLorentzTensor.ColorsIndex d (c x)
def IndexValue {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Color) :
Type 0 := (x : X) → ColorIndex d (c x)
def RealLorentzTensor.ColorFiber {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Colors) : Type :=
RealLorentzTensor.IndexValue d c → ℝ
instance [Fintype X] [DecidableEq X] : Fintype (IndexValue d c) := Pi.fintype
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Colors) :
AddCommMonoid (RealLorentzTensor.ColorFiber d c) := Pi.addCommMonoid
instance [Fintype X] : DecidableEq (IndexValue d c) :=
Fintype.decidablePiFintype
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Colors) :
Module ℝ (RealLorentzTensor.ColorFiber d c) := Pi.module _ _ _
def basisColorModule {d : ℕ} (μ : Color) :
Basis (ColorIndex d μ) ℝ (ColorModule d μ) := Pi.basisFun _ _
instance {X : Type} (d : ℕ) (c : X → RealLorentzTensor.Colors) :
AddCommGroup (RealLorentzTensor.ColorFiber d c) := Pi.addCommGroup
def basis (d : ℕ) (c : X → RealLorentzTensor.Color) :
Basis (IndexValue d c) ℝ (RealLorentzTensor d c) :=
Basis.piTensorProduct (fun x => basisColorModule (c x))
/-- A Lorentz Tensor defined by its coordinate map. -/
structure RealLorentzTensor (d : ℕ) (X : Type) where
/-- The color associated to each index of the tensor. -/
color : X → RealLorentzTensor.Colors
/-- The coordinate map for the tensor. -/
coord : RealLorentzTensor.ColorFiber d color
abbrev PiModule (d : ℕ) (c : X → Color) := IndexValue d c → ℝ
def asPi {d : ℕ} {c : X → Color} :
RealLorentzTensor d c ≃ₗ[ℝ] PiModule d c :=
(basis d c).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite ℝ ℝ (IndexValue d c)
namespace RealLorentzTensor
open Matrix
universe u1
variable {d : ℕ} {X Y Z : Type} (c : X → Colors)
/-!
@ -89,9 +138,9 @@ variable {d : ℕ} {X Y Z : Type} (c : X → Colors)
-/
/-- The involution acting on colors. -/
def τ : Colors → Colors
| Colors.up => Colors.down
| Colors.down => Colors.up
def τ : Color → Color
| Color.up => Color.down
| Color.down => Color.up
/-- The map τ is an involution. -/
@[simp]
@ -99,75 +148,71 @@ lemma τ_involutive : Function.Involutive τ := by
intro x
cases x <;> rfl
lemma color_eq_dual_symm {μ ν : Colors} (h : μ = τ ν) : ν = τ μ :=
lemma color_eq_dual_symm {μ ν : Color} (h : μ = τ ν) : ν = τ μ :=
(Function.Involutive.eq_iff τ_involutive).mp h.symm
lemma color_comp_τ_symm {c1 c2 : X → Colors} (h : c1 = τ ∘ c2) : c2 = τ ∘ c1 :=
lemma color_comp_τ_symm {c1 c2 : X → Color} (h : c1 = τ ∘ c2) : c2 = τ ∘ c1 :=
funext (fun x => color_eq_dual_symm (congrFun h x))
/-- The color associated with an element of `x ∈ X` for a tensor `T`. -/
def ch {X : Type} (x : X) (T : RealLorentzTensor d X) : Colors := T.color x
/-- An equivalence of `ColorsIndex` types given an equality of colors. -/
def colorsIndexCast {d : ℕ} {μ₁ μ₂ : RealLorentzTensor.Colors} (h : μ₁ = μ₂) :
ColorsIndex d μ₁ ≃ ColorsIndex d μ₂ :=
Equiv.cast (congrArg (ColorsIndex d) h)
/-- An equivalence of `ColorIndex` types given an equality of colors. -/
def colorIndexCast {d : ℕ} {μ₁ μ₂ : Color} (h : μ₁ = μ₂) :
ColorIndex d μ₁ ≃ ColorIndex d μ₂ :=
Equiv.cast (congrArg (ColorIndex d) h)
@[simp]
lemma colorsIndexCast_symm {d : ℕ} {μ₁ μ₂ : RealLorentzTensor.Colors} (h : μ₁ = μ₂) :
(@colorsIndexCast d _ _ h).symm = colorsIndexCast h.symm := by
lemma colorIndexCast_symm {d : ℕ} {μ₁ μ₂ : Color} (h : μ₁ = μ₂) :
(@colorIndexCast d _ _ h).symm = colorIndexCast h.symm := by
rfl
/-- An equivalence of `ColorsIndex` between that of a color and that of its dual. -/
def colorsIndexDualCastSelf {d : ℕ} {μ : RealLorentzTensor.Colors}:
ColorsIndex d μ ≃ ColorsIndex d (τ μ) where
/-- An equivalence of `ColorIndex` between that of a color and that of its dual.
I.e. the allowed index values for a color and its dual are equivalent. -/
def colorIndexDualCastSelf {d : ℕ} {μ : Color}:
ColorIndex d μ ≃ ColorIndex d (τ μ) where
toFun x :=
match μ with
| RealLorentzTensor.Colors.up => x
| RealLorentzTensor.Colors.down => x
| Color.up => x
| Color.down => x
invFun x :=
match μ with
| RealLorentzTensor.Colors.up => x
| RealLorentzTensor.Colors.down => x
| Color.up => x
| Color.down => x
left_inv x := by cases μ <;> rfl
right_inv x := by cases μ <;> rfl
/-- An equivalence of `ColorsIndex` types given an equality of a color and the dual of a color. -/
def colorsIndexDualCast {μ ν : Colors} (h : μ = τ ν) :
ColorsIndex d μ ≃ ColorsIndex d ν :=
(colorsIndexCast h).trans colorsIndexDualCastSelf.symm
/-- An equivalence between the allowed index values of a color and a color dual to it. -/
def colorIndexDualCast {μ ν : Color} (h : μ = τ ν) : ColorIndex d μ ≃ ColorIndex d ν :=
(colorIndexCast h).trans colorIndexDualCastSelf.symm
@[simp]
lemma colorsIndexDualCast_symm {μ ν : Colors} (h : μ = τ ν) :
(colorsIndexDualCast h).symm =
@colorsIndexDualCast d _ _ ((Function.Involutive.eq_iff τ_involutive).mp h.symm) := by
lemma colorIndexDualCast_symm {μ ν : Color} (h : μ = τ ν) : (colorIndexDualCast h).symm =
@colorIndexDualCast d _ _ ((Function.Involutive.eq_iff τ_involutive).mp h.symm) := by
match μ, ν with
| Colors.up, Colors.down => rfl
| Colors.down, Colors.up => rfl
| Color.up, Color.down => rfl
| Color.down, Color.up => rfl
@[simp]
lemma colorsIndexDualCast_trans {μ ν ξ : Colors} (h : μ = τ ν) (h' : ν = τ ξ) :
(@colorsIndexDualCast d _ _ h).trans (colorsIndexDualCast h') =
colorsIndexCast (by rw [h, h', τ_involutive]) := by
lemma colorIndexDualCast_trans {μ ν ξ : Color} (h : μ = τ ν) (h' : ν = τ ξ) :
(@colorIndexDualCast d _ _ h).trans (colorIndexDualCast h') =
colorIndexCast (by rw [h, h', τ_involutive]) := by
match μ, ν, ξ with
| Colors.up, Colors.down, Colors.up => rfl
| Colors.down, Colors.up, Colors.down => rfl
| Color.up, Color.down, Color.up => rfl
| Color.down, Color.up, Color.down => rfl
@[simp]
lemma colorsIndexDualCast_trans_colorsIndexCast {μ ν ξ : Colors} (h : μ = τ ν) (h' : ν = ξ) :
(@colorsIndexDualCast d _ _ h).trans (colorsIndexCast h') =
colorsIndexDualCast (by rw [h, h']) := by
lemma colorIndexDualCast_trans_colorsIndexCast {μ ν ξ : Color} (h : μ = τ ν) (h' : ν = ξ) :
(@colorIndexDualCast d _ _ h).trans (colorIndexCast h') =
colorIndexDualCast (by rw [h, h']) := by
match μ, ν, ξ with
| Colors.down, Colors.up, Colors.up => rfl
| Colors.up, Colors.down, Colors.down => rfl
| Color.down, Color.up, Color.up => rfl
| Color.up, Color.down, Color.down => rfl
@[simp]
lemma colorsIndexCast_trans_colorsIndexDualCast {μ ν ξ : Colors} (h : μ = ν) (h' : ν = τ ξ) :
(colorsIndexCast h).trans (@colorsIndexDualCast d _ _ h') =
colorsIndexDualCast (by rw [h, h']) := by
lemma colorIndexCast_trans_colorsIndexDualCast {μ ν ξ : Color} (h : μ = ν) (h' : ν = τ ξ) :
(colorIndexCast h).trans (@colorIndexDualCast d _ _ h') =
colorIndexDualCast (by rw [h, h']) := by
match μ, ν, ξ with
| Colors.up, Colors.up, Colors.down => rfl
| Colors.down, Colors.down, Colors.up => rfl
| Color.up, Color.up, Color.down => rfl
| Color.down, Color.down, Color.up => rfl
/-!
@ -176,10 +221,7 @@ lemma colorsIndexCast_trans_colorsIndexDualCast {μ ν ξ : Colors} (h : μ = ν
-/
instance [Fintype X] [DecidableEq X] : Fintype (IndexValue d c) := Pi.fintype
instance [Fintype X] : DecidableEq (IndexValue d c) :=
Fintype.decidablePiFintype
/-!
@ -188,20 +230,20 @@ instance [Fintype X] : DecidableEq (IndexValue d c) :=
-/
/-- An isomorphism of the type of index values given an isomorphism of sets. -/
def indexValueIso (d : ℕ) (f : X ≃ Y) {i : X → Colors} {j : Y → Colors} (h : i = j ∘ f) :
def indexValueIso (d : ℕ) (f : X ≃ Y) {i : X → Color} {j : Y → Color} (h : i = j ∘ f) :
IndexValue d i ≃ IndexValue d j :=
(Equiv.piCongrRight (fun μ => colorsIndexCast (congrFun h μ))).trans $
Equiv.piCongrLeft (fun y => RealLorentzTensor.ColorsIndex d (j y)) f
(Equiv.piCongrRight (fun μ => colorIndexCast (congrFun h μ))).trans $
Equiv.piCongrLeft (fun y => ColorIndex d (j y)) f
@[simp]
lemma indexValueIso_symm_apply' (d : ℕ) (f : X ≃ Y) {i : X → Colors} {j : Y → Colors}
lemma indexValueIso_symm_apply' (d : ℕ) (f : X ≃ Y) {i : X → Color} {j : Y → Color}
(h : i = j ∘ f) (y : IndexValue d j) (x : X) :
(indexValueIso d f h).symm y x = (colorsIndexCast (congrFun h x)).symm (y (f x)) := by
(indexValueIso d f h).symm y x = (colorIndexCast (congrFun h x)).symm (y (f x)) := by
rfl
@[simp]
lemma indexValueIso_trans (d : ℕ) (f : X ≃ Y) (g : Y ≃ Z) {i : X → Colors}
{j : Y → Colors} {k : Z → Colors} (h : i = j ∘ f) (h' : j = k ∘ g) :
lemma indexValueIso_trans (d : ℕ) (f : X ≃ Y) (g : Y ≃ Z) {i : X → Color}
{j : Y → Color} {k : Z → Color} (h : i = j ∘ f) (h' : j = k ∘ g) :
(indexValueIso d f h).trans (indexValueIso d g h') =
indexValueIso d (f.trans g) (by rw [h, h', Function.comp.assoc]; rfl) := by
have h1 : ((indexValueIso d f h).trans (indexValueIso d g h')).symm =
@ -218,7 +260,7 @@ lemma indexValueIso_symm (d : ℕ) (f : X ≃ Y) (h : i = j ∘ f) :
rw [← Equiv.symm_apply_eq]
funext y
rw [indexValueIso_symm_apply', indexValueIso_symm_apply']
simp only [Function.comp_apply, colorsIndexCast, Equiv.cast_symm, Equiv.cast_apply, cast_cast]
simp only [Function.comp_apply, colorIndexCast, Equiv.cast_symm, Equiv.cast_apply, cast_cast]
apply cast_eq_iff_heq.mpr
rw [Equiv.apply_symm_apply]
@ -229,7 +271,7 @@ lemma indexValueIso_eq_symm (d : ℕ) (f : X ≃ Y) (h : i = j ∘ f) :
rfl
@[simp]
lemma indexValueIso_refl (d : ℕ) (i : X → Colors) :
lemma indexValueIso_refl (d : ℕ) (i : X → Color) :
indexValueIso d (Equiv.refl X) (rfl : i = i) = Equiv.refl _ := by
rfl
@ -242,17 +284,17 @@ lemma indexValueIso_refl (d : ℕ) (i : X → Colors) :
-/
/-- The isomorphism between the index values of a color map and its dual. -/
def indexValueDualIso (d : ℕ) {i : X → Colors} {j : Y → Colors} (e : X ≃ Y)
def indexValueDualIso (d : ℕ) {i : X → Color} {j : Y → Color} (e : X ≃ Y)
(h : i = τ ∘ j ∘ e) : IndexValue d i ≃ IndexValue d j :=
(Equiv.piCongrRight (fun μ => colorsIndexDualCast (congrFun h μ))).trans $
Equiv.piCongrLeft (fun y => ColorsIndex d (j y)) e
(Equiv.piCongrRight (fun μ => colorIndexDualCast (congrFun h μ))).trans $
Equiv.piCongrLeft (fun y => ColorIndex d (j y)) e
lemma indexValueDualIso_symm_apply' (d : ℕ) {i : X → Colors} {j : Y → Colors} (e : X ≃ Y)
lemma indexValueDualIso_symm_apply' (d : ℕ) {i : X → Color} {j : Y → Color} (e : X ≃ Y)
(h : i = τ ∘ j ∘ e) (y : IndexValue d j) (x : X) :
(indexValueDualIso d e h).symm y x = (colorsIndexDualCast (congrFun h x)).symm (y (e x)) := by
(indexValueDualIso d e h).symm y x = (colorIndexDualCast (congrFun h x)).symm (y (e x)) := by
rfl
lemma indexValueDualIso_cond_symm {i : X → Colors} {j : Y → Colors} {e : X ≃ Y}
lemma indexValueDualIso_cond_symm {i : X → Color} {j : Y → Color} {e : X ≃ Y}
(h : i = τ ∘ j ∘ e) : j = τ ∘ i ∘ e.symm := by
subst h
simp only [Function.comp.assoc, Equiv.self_comp_symm, CompTriple.comp_eq]
@ -261,26 +303,26 @@ lemma indexValueDualIso_cond_symm {i : X → Colors} {j : Y → Colors} {e : X
simp only [τ_involutive, Function.Involutive.comp_self, Function.comp_apply, id_eq]
@[simp]
lemma indexValueDualIso_symm {d : ℕ} {i : X → Colors} {j : Y → Colors} (e : X ≃ Y)
lemma indexValueDualIso_symm {d : ℕ} {i : X → Color} {j : Y → Color} (e : X ≃ Y)
(h : i = τ ∘ j ∘ e) : (indexValueDualIso d e h).symm =
indexValueDualIso d e.symm (indexValueDualIso_cond_symm h) := by
ext i : 1
rw [← Equiv.symm_apply_eq]
funext a
rw [indexValueDualIso_symm_apply', indexValueDualIso_symm_apply']
erw [← Equiv.trans_apply, colorsIndexDualCast_symm, colorsIndexDualCast_symm,
colorsIndexDualCast_trans]
simp only [Function.comp_apply, colorsIndexCast, Equiv.cast_apply]
erw [← Equiv.trans_apply, colorIndexDualCast_symm, colorIndexDualCast_symm,
colorIndexDualCast_trans]
simp only [Function.comp_apply, colorIndexCast, Equiv.cast_apply]
apply cast_eq_iff_heq.mpr
rw [Equiv.apply_symm_apply]
lemma indexValueDualIso_eq_symm {d : ℕ} {i : X → Colors} {j : Y → Colors} (e : X ≃ Y)
lemma indexValueDualIso_eq_symm {d : ℕ} {i : X → Color} {j : Y → Color} (e : X ≃ Y)
(h : i = τ ∘ j ∘ e) :
indexValueDualIso d e h = (indexValueDualIso d e.symm (indexValueDualIso_cond_symm h)).symm := by
rw [indexValueDualIso_symm]
simp
lemma indexValueDualIso_cond_trans {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueDualIso_cond_trans {i : X → Color} {j : Y → Color} {k : Z → Color}
{e : X ≃ Y} {f : Y ≃ Z} (h : i = τ ∘ j ∘ e) (h' : j = τ ∘ k ∘ f) :
i = k ∘ (e.trans f) := by
rw [h, h']
@ -289,7 +331,7 @@ lemma indexValueDualIso_cond_trans {i : X → Colors} {j : Y → Colors} {k : Z
rw [τ_involutive]
@[simp]
lemma indexValueDualIso_trans {d : ℕ} {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueDualIso_trans {d : ℕ} {i : X → Color} {j : Y → Color} {k : Z → Color}
(e : X ≃ Y) (f : Y ≃ Z) (h : i = τ ∘ j ∘ e) (h' : j = τ ∘ k ∘ f) :
(indexValueDualIso d e h).trans (indexValueDualIso d f h') =
indexValueIso d (e.trans f) (indexValueDualIso_cond_trans h h') := by
@ -300,14 +342,14 @@ lemma indexValueDualIso_trans {d : ℕ} {i : X → Colors} {j : Y → Colors} {k
rw [indexValueDualIso_symm_apply', indexValueDualIso_symm_apply',
indexValueIso_symm_apply']
erw [← Equiv.trans_apply]
rw [colorsIndexDualCast_symm, colorsIndexDualCast_symm, colorsIndexDualCast_trans]
simp only [Function.comp_apply, colorsIndexCast, Equiv.symm_trans_apply, Equiv.cast_symm,
rw [colorIndexDualCast_symm, colorIndexDualCast_symm, colorIndexDualCast_trans]
simp only [Function.comp_apply, colorIndexCast, Equiv.symm_trans_apply, Equiv.cast_symm,
Equiv.cast_apply, cast_cast]
symm
apply cast_eq_iff_heq.mpr
rw [Equiv.symm_apply_apply, Equiv.symm_apply_apply]
lemma indexValueDualIso_cond_trans_indexValueIso {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueDualIso_cond_trans_indexValueIso {i : X → Color} {j : Y → Color} {k : Z → Color}
{e : X ≃ Y} {f : Y ≃ Z} (h : i = τ ∘ j ∘ e) (h' : j = k ∘ f) :
i = τ ∘ k ∘ (e.trans f) := by
rw [h, h']
@ -315,7 +357,7 @@ lemma indexValueDualIso_cond_trans_indexValueIso {i : X → Colors} {j : Y → C
simp only [Function.comp_apply, Equiv.coe_trans]
@[simp]
lemma indexValueDualIso_trans_indexValueIso {d : ℕ} {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueDualIso_trans_indexValueIso {d : ℕ} {i : X → Color} {j : Y → Color} {k : Z → Color}
(e : X ≃ Y) (f : Y ≃ Z) (h : i = τ ∘ j ∘ e) (h' : j = k ∘ f) :
(indexValueDualIso d e h).trans (indexValueIso d f h') =
indexValueDualIso d (e.trans f) (indexValueDualIso_cond_trans_indexValueIso h h') := by
@ -326,14 +368,14 @@ lemma indexValueDualIso_trans_indexValueIso {d : ℕ} {i : X → Colors} {j : Y
indexValueIso_symm_apply',indexValueDualIso_eq_symm, indexValueDualIso_symm_apply']
rw [Equiv.symm_apply_eq]
erw [← Equiv.trans_apply, ← Equiv.trans_apply]
simp only [Function.comp_apply, Equiv.symm_trans_apply, colorsIndexDualCast_symm,
colorsIndexCast_symm, colorsIndexCast_trans_colorsIndexDualCast, colorsIndexDualCast_trans]
simp only [colorsIndexCast, Equiv.cast_apply]
simp only [Function.comp_apply, Equiv.symm_trans_apply, colorIndexDualCast_symm,
colorIndexCast_symm, colorIndexCast_trans_colorsIndexDualCast, colorIndexDualCast_trans]
simp only [colorIndexCast, Equiv.cast_apply]
symm
apply cast_eq_iff_heq.mpr
rw [Equiv.symm_apply_apply]
lemma indexValueIso_trans_indexValueDualIso_cond {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueIso_trans_indexValueDualIso_cond {i : X → Color} {j : Y → Color} {k : Z → Color}
{e : X ≃ Y} {f : Y ≃ Z} (h : i = j ∘ e) (h' : j = τ ∘ k ∘ f) :
i = τ ∘ k ∘ (e.trans f) := by
rw [h, h']
@ -341,7 +383,7 @@ lemma indexValueIso_trans_indexValueDualIso_cond {i : X → Colors} {j : Y → C
simp only [Function.comp_apply, Equiv.coe_trans]
@[simp]
lemma indexValueIso_trans_indexValueDualIso {d : ℕ} {i : X → Colors} {j : Y → Colors} {k : Z → Colors}
lemma indexValueIso_trans_indexValueDualIso {d : ℕ} {i : X → Color} {j : Y → Color} {k : Z → Color}
(e : X ≃ Y) (f : Y ≃ Z) (h : i = j ∘ e) (h' : j = τ ∘ k ∘ f) :
(indexValueIso d e h).trans (indexValueDualIso d f h') =
indexValueDualIso d (e.trans f) (indexValueIso_trans_indexValueDualIso_cond h h') := by
@ -351,9 +393,9 @@ lemma indexValueIso_trans_indexValueDualIso {d : ℕ} {i : X → Colors} {j : Y
rw [indexValueIso_symm_apply', indexValueDualIso_symm_apply',
indexValueDualIso_eq_symm, indexValueDualIso_symm_apply']
erw [← Equiv.trans_apply, ← Equiv.trans_apply]
simp only [Function.comp_apply, Equiv.symm_trans_apply, colorsIndexDualCast_symm,
colorsIndexCast_symm, colorsIndexDualCast_trans_colorsIndexCast, colorsIndexDualCast_trans]
simp only [colorsIndexCast, Equiv.cast_apply]
simp only [Function.comp_apply, Equiv.symm_trans_apply, colorIndexDualCast_symm,
colorIndexCast_symm, colorIndexDualCast_trans_colorsIndexCast, colorIndexDualCast_trans]
simp only [colorIndexCast, Equiv.cast_apply]
symm
apply cast_eq_iff_heq.mpr
rw [Equiv.symm_apply_apply, Equiv.symm_apply_apply]
@ -367,8 +409,8 @@ lemma indexValueIso_trans_indexValueDualIso {d : ℕ} {i : X → Colors} {j : Y
-/
@[simps!]
def mapIsoFiber (d : ℕ) (f : X ≃ Y) {i : X → Colors} {j : Y → Colors} (h : i = j ∘ f) :
ColorFiber d i ≃ₗ[ℝ] ColorFiber d j where
def mapIso {d : ℕ} (f : X ≃ Y) {i : X → Color} {j : Y → Color} (h : i = j ∘ f) :
RealLorentzTensor d i ≃ₗ[ℝ] RealLorentzTensor d j where
toFun F := F ∘ (indexValueIso d f h).symm
invFun F := F ∘ indexValueIso d f h
map_add' F G := by rfl
@ -383,82 +425,21 @@ def mapIsoFiber (d : ℕ) (f : X ≃ Y) {i : X → Colors} {j : Y → Colors} (h
exact congrArg _ $ Equiv.apply_symm_apply (indexValueIso d f h) x
@[simp]
lemma mapIsoFiber_trans (d : ℕ) (f : X ≃ Y) (g : Y ≃ Z) {i : X → Colors}
{j : Y → Colors} {k : Z → Colors} (h : i = j ∘ f) (h' : j = k ∘ g) :
(mapIsoFiber d f h).trans (mapIsoFiber d g h') =
mapIsoFiber d (f.trans g) (by rw [h, h', Function.comp.assoc]; rfl) := by
lemma mapIso_trans (d : ℕ) (f : X ≃ Y) (g : Y ≃ Z) {i : X → Color}
{j : Y → Color} {k : Z → Color} (h : i = j ∘ f) (h' : j = k ∘ g) :
(@mapIso _ _ d f _ _ h).trans (mapIso g h') =
mapIso (f.trans g) (by rw [h, h', Function.comp.assoc]; rfl) := by
refine LinearEquiv.toEquiv_inj.mp (Equiv.ext (fun x => (funext (fun a => ?_))))
simp only [LinearEquiv.coe_toEquiv, LinearEquiv.trans_apply, mapIsoFiber_apply,
simp only [LinearEquiv.coe_toEquiv, LinearEquiv.trans_apply, mapIso_apply,
indexValueIso_symm, ← Equiv.trans_apply, indexValueIso_trans]
rfl
lemma mapIsoFiber_symm (d : ℕ) (f : X ≃ Y) (h : i = j ∘ f) :
(mapIsoFiber d f h).symm = mapIsoFiber d f.symm ((Equiv.eq_comp_symm f j i).mpr h.symm) := by
lemma mapIso_symm (d : ℕ) (f : X ≃ Y) (h : i = j ∘ f) :
(@mapIso _ _ d f _ _ h).symm = mapIso f.symm ((Equiv.eq_comp_symm f j i).mpr h.symm) := by
refine LinearEquiv.toEquiv_inj.mp (Equiv.ext (fun x => (funext (fun a => ?_))))
simp only [LinearEquiv.coe_toEquiv, mapIsoFiber_symm_apply, mapIsoFiber_apply, indexValueIso_symm,
simp only [LinearEquiv.coe_toEquiv, mapIso_symm_apply, mapIso_apply, indexValueIso_symm,
Equiv.symm_symm]
/-!
## Extensionality
-/
lemma ext {T₁ T₂ : RealLorentzTensor d X} (h : T₁.color = T₂.color)
(h' : T₁.coord = mapIsoFiber d (Equiv.refl X) h.symm T₂.coord) : T₁ = T₂ := by
cases T₁
cases T₂
simp_all only [IndexValue, mk.injEq]
apply And.intro h
simp only at h
subst h
rfl
/-!
## Mapping isomorphisms
-/
/-- An equivalence of Tensors given an equivalence of underlying sets. -/
@[simps!]
def mapIso (d : ℕ) (f : X ≃ Y) : RealLorentzTensor d X ≃ RealLorentzTensor d Y where
toFun T := ⟨T.color ∘ f.symm, mapIsoFiber d f (by funext x; simp) T.coord⟩
invFun T := ⟨T.color ∘ f, (mapIsoFiber d f (by funext x; simp)).symm T.coord⟩
left_inv T := by
refine ext ?_ ?_
· simp [Function.comp.assoc]
· simp only [Function.comp_apply, ← LinearEquiv.trans_apply, mapIsoFiber_symm,
mapIsoFiber_trans]
congr
exact Equiv.self_trans_symm f
right_inv T := by
refine ext ?_ ?_
· simp [Function.comp.assoc]
· simp only [Function.comp_apply, ← LinearEquiv.trans_apply, mapIsoFiber_symm,
mapIsoFiber_trans]
congr
exact Equiv.symm_trans_self f
@[simp]
lemma mapIso_trans (f : X ≃ Y) (g : Y ≃ Z) :
(mapIso d f).trans (mapIso d g) = mapIso d (f.trans g) := by
refine Equiv.coe_inj.mp ?_
funext T
refine ext rfl ?_
simp
erw [← LinearEquiv.trans_apply, ← LinearEquiv.trans_apply, mapIsoFiber_trans, mapIsoFiber_trans]
rfl
lemma mapIso_symm (f : X ≃ Y) : (mapIso d f).symm = mapIso d f.symm := by
refine Equiv.coe_inj.mp ?_
funext T
refine ext rfl ?_
erw [← LinearEquiv.trans_apply]
rw [mapIso_symm_apply_coord, mapIsoFiber_trans, mapIsoFiber_symm]
rfl
lemma mapIso_refl : mapIso d (Equiv.refl X) = Equiv.refl _ := rfl
/-!
@ -467,7 +448,7 @@ lemma mapIso_refl : mapIso d (Equiv.refl X) = Equiv.refl _ := rfl
-/
/-- An equivalence that splits elements of `IndexValue d (Sum.elim TX TY)` into two components. -/
def indexValueSumEquiv {X Y : Type} {TX : X → Colors} {TY : Y → Colors} :
def indexValueTensorator {X Y : Type} {TX : X → Color} {TY : Y → Color} :
IndexValue d (Sum.elim TX TY) ≃ IndexValue d TX × IndexValue d TY where
toFun i := (fun x => i (Sum.inl x), fun x => i (Sum.inr x))
invFun p := fun c => match c with
@ -481,338 +462,37 @@ def indexValueSumEquiv {X Y : Type} {TX : X → Colors} {TY : Y → Colors} :
| inr val_1 => rfl
right_inv p := rfl
/-- An equivalence between index values formed by commuting sums. -/
def indexValueSumComm {X Y : Type} (Tc : X → Colors) (Sc : Y → Colors) :
IndexValue d (Sum.elim Tc Sc) ≃ IndexValue d (Sum.elim Sc Tc) :=
indexValueIso d (Equiv.sumComm X Y) (by aesop)
def indexValueFinOne {c : Fin 1 → Colors} :
ColorsIndex d (c 0) ≃ IndexValue d c where
toFun x := fun i => match i with
| 0 => x
invFun i := i 0
left_inv x := rfl
right_inv i := by
funext x
fin_cases x
rfl
/-!
## Marked Lorentz tensors
To define contraction and multiplication of Lorentz tensors we need to mark indices.
-/
/-- A `RealLorentzTensor` with `n` marked indices. -/
def Marked (d : ℕ) (X : Type) (n : ℕ) : Type :=
RealLorentzTensor d (X ⊕ Fin n)
namespace Marked
variable {n m : ℕ}
/-- The marked point. -/
def markedPoint (X : Type) (i : Fin n) : (X ⊕ Fin n) :=
Sum.inr i
/-- The colors of unmarked indices. -/
def unmarkedColor (T : Marked d X n) : X → Colors :=
T.color ∘ Sum.inl
/-- The colors of marked indices. -/
def markedColor (T : Marked d X n) : Fin n → Colors :=
T.color ∘ Sum.inr
/-- The index values restricted to unmarked indices. -/
def UnmarkedIndexValue (T : Marked d X n) : Type :=
IndexValue d T.unmarkedColor
instance [Fintype X] [DecidableEq X] (T : Marked d X n) : Fintype T.UnmarkedIndexValue :=
Pi.fintype
instance [Fintype X] (T : Marked d X n) : DecidableEq T.UnmarkedIndexValue :=
Fintype.decidablePiFintype
/-- The index values restricted to marked indices. -/
def MarkedIndexValue (T : Marked d X n) : Type :=
IndexValue d T.markedColor
instance (T : Marked d X n) : Fintype T.MarkedIndexValue :=
Pi.fintype
instance (T : Marked d X n) : DecidableEq T.MarkedIndexValue :=
Fintype.decidablePiFintype
lemma color_eq_elim (T : Marked d X n) :
T.color = Sum.elim T.unmarkedColor T.markedColor := by
/-! TODO : Move -/
lemma tensorator_mapIso_cond {cX : X → Color} {cY : Y → Color} {cX' : X' → Color}
{cY' : Y' → Color} {eX : X ≃ X'} {eY : Y ≃ Y'} (hX : cX = cX' ∘ eX) (hY : cY = cY' ∘ eY) :
Sum.elim cX cY = Sum.elim cX' cY' ∘ ⇑(eX.sumCongr eY) := by
subst hX hY
ext1 x
cases' x <;> rfl
simp_all only [Function.comp_apply, Equiv.sumCongr_apply]
cases x with
| inl val => simp_all only [Sum.elim_inl, Function.comp_apply, Sum.map_inl]
| inr val_1 => simp_all only [Sum.elim_inr, Function.comp_apply, Sum.map_inr]
/-- An equivalence splitting elements of `IndexValue d T.color` into their two components. -/
def splitIndexValue {T : Marked d X n} :
IndexValue d T.color ≃ T.UnmarkedIndexValue × T.MarkedIndexValue :=
(indexValueIso d (Equiv.refl _) T.color_eq_elim).trans
indexValueSumEquiv
@[simp]
lemma splitIndexValue_sum {T : Marked d X n} [Fintype X] [DecidableEq X]
(P : T.UnmarkedIndexValue × T.MarkedIndexValue → ℝ) :
∑ i, P (splitIndexValue i) = ∑ j, ∑ k, P (j, k) := by
rw [Equiv.sum_comp splitIndexValue, Fintype.sum_prod_type]
/-- Construction of marked index values for the case of 1 marked index. -/
def oneMarkedIndexValue {T : Marked d X 1} :
ColorsIndex d (T.color (markedPoint X 0)) ≃ T.MarkedIndexValue where
toFun x := fun i => match i with
| 0 => x
invFun i := i 0
left_inv x := rfl
right_inv i := by
lemma indexValueTensorator_indexValueMapIso {cX : X → Color} {cY : Y → Color} {cX' : X' → Color}
{cY' : Y' → Color} (eX : X ≃ X') (eY : Y ≃ Y') (hX : cX = cX' ∘ eX) (hY : cY = cY' ∘ eY) :
(indexValueIso d (Equiv.sumCongr eX eY) (tensorator_mapIso_cond hX hY)).trans indexValueTensorator =
indexValueTensorator.trans (Equiv.prodCongr (indexValueIso d eX hX) (indexValueIso d eY hY)) := by
apply Equiv.ext
intro i
simp
simp [ indexValueTensorator]
apply And.intro
all_goals
funext x
fin_cases x
rfl
/-- Construction of marked index values for the case of 2 marked index. -/
def twoMarkedIndexValue (T : Marked d X 2) (x : ColorsIndex d (T.color (markedPoint X 0)))
(y : ColorsIndex d <| T.color <| markedPoint X 1) :
T.MarkedIndexValue := fun i =>
match i with
| 0 => x
| 1 => y
/-- An equivalence of types used to turn the first marked index into an unmarked index. -/
def unmarkFirstSet (X : Type) (n : ℕ) : (X ⊕ Fin n.succ) ≃ (X ⊕ Fin 1) ⊕ Fin n :=
trans (Equiv.sumCongr (Equiv.refl _)
(((Fin.castOrderIso (Nat.succ_eq_one_add n)).toEquiv.trans finSumFinEquiv.symm)))
(Equiv.sumAssoc _ _ _).symm
/-- Unmark the first marked index of a marked tensor. -/
def unmarkFirst {X : Type} : Marked d X n.succ ≃ Marked d (X ⊕ Fin 1) n :=
mapIso d (unmarkFirstSet X n)
rw [indexValueIso_eq_symm, indexValueIso_symm_apply']
rw [indexValueIso_eq_symm, indexValueIso_symm_apply']
simp
/-!
## Marking elements.
## A basis for Lorentz tensors
-/
section markingElements
variable [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
/-- Splits a type based on an embedding from `Fin n` into elements not in the image of the
embedding, and elements in the image. -/
def markEmbeddingSet {n : ℕ} (f : Fin n ↪ X) :
X ≃ {x // x ∈ (Finset.image f Finset.univ)ᶜ} ⊕ Fin n :=
(Equiv.Set.sumCompl (Set.range ⇑f)).symm.trans <|
(Equiv.sumComm _ _).trans <|
Equiv.sumCongr ((Equiv.subtypeEquivRight (by simp))) <|
(Function.Embedding.toEquivRange f).symm
lemma markEmbeddingSet_on_mem {n : ℕ} (f : Fin n ↪ X) (x : X)
(hx : x ∈ Finset.image f Finset.univ) : markEmbeddingSet f x =
Sum.inr (f.toEquivRange.symm ⟨x, by simpa using hx⟩) := by
rw [markEmbeddingSet]
simp only [Equiv.trans_apply, Equiv.sumComm_apply, Equiv.sumCongr_apply]
rw [Equiv.Set.sumCompl_symm_apply_of_mem]
rfl
lemma markEmbeddingSet_on_not_mem {n : ℕ} (f : Fin n ↪ X) (x : X)
(hx : ¬ x ∈ (Finset.image f Finset.univ)) : markEmbeddingSet f x =
Sum.inl ⟨x, by simpa using hx⟩ := by
rw [markEmbeddingSet]
simp only [Equiv.trans_apply, Equiv.sumComm_apply, Equiv.sumCongr_apply]
rw [Equiv.Set.sumCompl_symm_apply_of_not_mem]
rfl
simpa using hx
/-- Marks the indices of tensor in the image of an embedding. -/
@[simps!]
def markEmbedding {n : ℕ} (f : Fin n ↪ X) :
RealLorentzTensor d X ≃ Marked d {x // x ∈ (Finset.image f Finset.univ)ᶜ} n :=
mapIso d (markEmbeddingSet f)
lemma markEmbeddingSet_on_mem_indexValue_apply {n : ℕ} (f : Fin n ↪ X) (T : RealLorentzTensor d X)
(i : IndexValue d (markEmbedding f T).color) (x : X) (hx : x ∈ (Finset.image f Finset.univ)) :
i (markEmbeddingSet f x) = colorsIndexCast (congrArg ((markEmbedding f) T).color
(markEmbeddingSet_on_mem f x hx).symm)
(i (Sum.inr (f.toEquivRange.symm ⟨x, by simpa using hx⟩))) := by
simp [colorsIndexCast]
symm
apply cast_eq_iff_heq.mpr
rw [markEmbeddingSet_on_mem f x hx]
lemma markEmbeddingSet_on_not_mem_indexValue_apply {n : ℕ}
(f : Fin n ↪ X) (T : RealLorentzTensor d X) (i : IndexValue d (markEmbedding f T).color)
(x : X) (hx : ¬ x ∈ (Finset.image f Finset.univ)) :
i (markEmbeddingSet f x) = colorsIndexCast (congrArg ((markEmbedding f) T).color
(markEmbeddingSet_on_not_mem f x hx).symm) (i (Sum.inl ⟨x, by simpa using hx⟩)) := by
simp [colorsIndexCast]
symm
apply cast_eq_iff_heq.mpr
rw [markEmbeddingSet_on_not_mem f x hx]
/-- An equivalence between the IndexValues for a tensor `T` and the corresponding
tensor with indices maked by an embedding. -/
@[simps!]
def markEmbeddingIndexValue {n : ℕ} (f : Fin n ↪ X) (T : RealLorentzTensor d X) :
IndexValue d T.color ≃ IndexValue d (markEmbedding f T).color :=
indexValueIso d (markEmbeddingSet f) (
(Equiv.comp_symm_eq (markEmbeddingSet f) ((markEmbedding f) T).color T.color).mp rfl)
lemma markEmbeddingIndexValue_apply_symm_on_mem {n : ℕ}
(f : Fin n.succ ↪ X) (T : RealLorentzTensor d X) (i : IndexValue d (markEmbedding f T).color)
(x : X) (hx : x ∈ (Finset.image f Finset.univ)) :
(markEmbeddingIndexValue f T).symm i x = (colorsIndexCast ((congrFun ((Equiv.comp_symm_eq
(markEmbeddingSet f) ((markEmbedding f) T).color T.color).mp rfl) x).trans
(congrArg ((markEmbedding f) T).color (markEmbeddingSet_on_mem f x hx)))).symm
(i (Sum.inr (f.toEquivRange.symm ⟨x, by simpa using hx⟩))) := by
rw [markEmbeddingIndexValue, indexValueIso_symm_apply']
rw [markEmbeddingSet_on_mem_indexValue_apply f T i x hx]
simp [colorsIndexCast]
lemma markEmbeddingIndexValue_apply_symm_on_not_mem {n : ℕ} (f : Fin n.succ ↪ X)
(T : RealLorentzTensor d X) (i : IndexValue d (markEmbedding f T).color) (x : X)
(hx : ¬ x ∈ (Finset.image f Finset.univ)) : (markEmbeddingIndexValue f T).symm i x =
(colorsIndexCast ((congrFun ((Equiv.comp_symm_eq
(markEmbeddingSet f) ((markEmbedding f) T).color T.color).mp rfl) x).trans
((congrArg ((markEmbedding f) T).color (markEmbeddingSet_on_not_mem f x hx))))).symm
(i (Sum.inl ⟨x, by simpa using hx⟩)) := by
rw [markEmbeddingIndexValue, indexValueIso_symm_apply']
rw [markEmbeddingSet_on_not_mem_indexValue_apply f T i x hx]
simp only [Nat.succ_eq_add_one, Function.comp_apply, markEmbedding_apply_color, colorsIndexCast,
Equiv.cast_symm, id_eq, eq_mp_eq_cast, eq_mpr_eq_cast, Equiv.cast_apply, cast_cast, cast_eq,
Equiv.cast_refl, Equiv.refl_symm]
rfl
/-- Given an equivalence of types, an embedding `f` to an embedding `g`, the equivalence
taking the complement of the image of `f` to the complement of the image of `g`. -/
@[simps!]
def equivEmbedCompl (e : X ≃ Y) {f : Fin n ↪ X} {g : Fin n ↪ Y} (he : f.trans e = g) :
{x // x ∈ (Finset.image f Finset.univ)ᶜ} ≃ {y // y ∈ (Finset.image g Finset.univ)ᶜ} :=
(Equiv.subtypeEquivOfSubtype' e).trans <|
(Equiv.subtypeEquivRight (fun x => by simp [← he, Equiv.eq_symm_apply]))
lemma markEmbedding_mapIso_right (e : X ≃ Y) (f : Fin n ↪ X) (g : Fin n ↪ Y) (he : f.trans e = g)
(T : RealLorentzTensor d X) : markEmbedding g (mapIso d e T) =
mapIso d (Equiv.sumCongr (equivEmbedCompl e he) (Equiv.refl (Fin n))) (markEmbedding f T) := by
rw [markEmbedding, markEmbedding]
erw [← Equiv.trans_apply, ← Equiv.trans_apply]
rw [mapIso_trans, mapIso_trans]
apply congrFun
repeat apply congrArg
refine Equiv.ext (fun x => ?_)
simp only [Equiv.trans_apply, Equiv.sumCongr_apply, Equiv.coe_refl]
by_cases hx : x ∈ Finset.image f Finset.univ
· rw [markEmbeddingSet_on_mem f x hx, markEmbeddingSet_on_mem g (e x) (by simpa [← he] using hx)]
subst he
simp only [Sum.map_inr, id_eq, Sum.inr.injEq, Equiv.symm_apply_eq,
Function.Embedding.toEquivRange_apply, Function.Embedding.trans_apply, Equiv.coe_toEmbedding,
Subtype.mk.injEq, EmbeddingLike.apply_eq_iff_eq]
change x = f.toEquivRange _
rw [Equiv.apply_symm_apply]
· rw [markEmbeddingSet_on_not_mem f x hx,
markEmbeddingSet_on_not_mem g (e x) (by simpa [← he] using hx)]
subst he
rfl
lemma markEmbedding_mapIso_left {n m : ℕ} (e : Fin n ≃ Fin m) (f : Fin n ↪ X) (g : Fin m ↪ X)
(he : e.symm.toEmbedding.trans f = g) (T : RealLorentzTensor d X) :
markEmbedding g T = mapIso d (Equiv.sumCongr (Equiv.subtypeEquivRight (fun x => by
simpa [← he] using Equiv.forall_congr_left e)) e) (markEmbedding f T) := by
rw [markEmbedding, markEmbedding]
erw [← Equiv.trans_apply]
rw [mapIso_trans]
apply congrFun
repeat apply congrArg
refine Equiv.ext (fun x => ?_)
simp only [Equiv.trans_apply, Equiv.sumCongr_apply]
by_cases hx : x ∈ Finset.image f Finset.univ
· rw [markEmbeddingSet_on_mem f x hx, markEmbeddingSet_on_mem g x (by
simp [← he, hx]
obtain ⟨y, _, hy2⟩ := Finset.mem_image.mp hx
use e y
simpa using hy2)]
subst he
simp [Equiv.symm_apply_eq]
change x = f.toEquivRange _
rw [Equiv.apply_symm_apply]
· rw [markEmbeddingSet_on_not_mem f x hx, markEmbeddingSet_on_not_mem g x (by
simpa [← he, hx] using fun x => not_exists.mp (Finset.mem_image.mpr.mt hx) (e.symm x))]
subst he
rfl
/-!
## Marking a single element
-/
/-- An embedding from `Fin 1` into `X` given an element `x ∈ X`. -/
@[simps!]
def embedSingleton (x : X) : Fin 1 ↪ X :=
⟨![x], fun x y => by fin_cases x; fin_cases y; simp⟩
lemma embedSingleton_toEquivRange_symm (x : X) :
(embedSingleton x).toEquivRange.symm ⟨x, by simp⟩ = 0 := by
exact Fin.fin_one_eq_zero _
/-- Equivalence, taking a tensor to a tensor with a single marked index. -/
@[simps!]
def markSingle (x : X) : RealLorentzTensor d X ≃ Marked d {x' // x' ≠ x} 1 :=
(markEmbedding (embedSingleton x)).trans
(mapIso d (Equiv.sumCongr (Equiv.subtypeEquivRight (fun x => by simp)) (Equiv.refl _)))
/-- Equivalence between index values of a tensor and the corresponding tensor with a single
marked index. -/
@[simps!]
def markSingleIndexValue (T : RealLorentzTensor d X) (x : X) :
IndexValue d T.color ≃ IndexValue d (markSingle x T).color :=
(markEmbeddingIndexValue (embedSingleton x) T).trans <|
indexValueIso d (Equiv.sumCongr (Equiv.subtypeEquivRight (fun x => by simp)) (Equiv.refl _))
(by funext x_1; simp)
/-- Given an equivalence of types, taking `x` to `y` the corresponding equivalence of
subtypes of elements not equal to `x` and not equal to `y` respectively. -/
@[simps!]
def equivSingleCompl (e : X ≃ Y) {x : X} {y : Y} (he : e x = y) :
{x' // x' ≠ x} ≃ {y' // y' ≠ y} :=
(Equiv.subtypeEquivOfSubtype' e).trans <|
Equiv.subtypeEquivRight (fun a => by simp [Equiv.symm_apply_eq, he])
lemma markSingle_mapIso (e : X ≃ Y) (x : X) (y : Y) (he : e x = y)
(T : RealLorentzTensor d X) : markSingle y (mapIso d e T) =
mapIso d (Equiv.sumCongr (equivSingleCompl e he) (Equiv.refl _)) (markSingle x T) := by
rw [markSingle, Equiv.trans_apply]
rw [markEmbedding_mapIso_right e (embedSingleton x) (embedSingleton y)
(Function.Embedding.ext_iff.mp (fun a => by simpa using he)), markSingle, markEmbedding]
erw [← Equiv.trans_apply, ← Equiv.trans_apply, ← Equiv.trans_apply]
rw [mapIso_trans, mapIso_trans, mapIso_trans, mapIso_trans]
apply congrFun
repeat apply congrArg
refine Equiv.ext fun x => ?_
simp only [ne_eq, Fintype.univ_ofSubsingleton, Fin.zero_eta, Fin.isValue, Equiv.sumCongr_trans,
Equiv.trans_refl, Equiv.trans_apply, Equiv.sumCongr_apply, Equiv.coe_trans, Equiv.coe_refl,
Sum.map_map, CompTriple.comp_eq]
subst he
rfl
/-!
## Marking two elements
-/
/-- An embedding from `Fin 2` given two inequivalent elements. -/
@[simps!]
def embedDoubleton (x y : X) (h : x ≠ y) : Fin 2 ↪ X :=
⟨![x, y], fun a b => by
fin_cases a <;> fin_cases b <;> simp [h]
exact h.symm⟩
end markingElements
end Marked
noncomputable section basis
@ -821,28 +501,28 @@ open Set LinearMap Submodule
variable {d : ℕ} {X Y Y' X' : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
[Fintype Y'] [DecidableEq Y'] [Fintype X'] [DecidableEq X']
(cX : X → Colors) (cY : Y → Colors)
(cX : X → Color) (cY : Y → Color)
def basisColorFiber : Basis (IndexValue d cX) ℝ (ColorFiber d cX) := Pi.basisFun _ _
def basis : Basis (IndexValue d cX) ℝ (RealLorentzTensor d cX) := Pi.basisFun _ _
@[simp]
def basisProd :
Basis (IndexValue d cX × IndexValue d cY) ℝ (ColorFiber d cX ⊗[ℝ] ColorFiber d cY) :=
(Basis.tensorProduct (basisColorFiber cX) (basisColorFiber cY))
Basis (IndexValue d cX × IndexValue d cY) ℝ (RealLorentzTensor d cX ⊗[ℝ] RealLorentzTensor d cY) :=
(Basis.tensorProduct (basis cX) (basis cY))
lemma mapIsoFiber_basis {cX : X → Colors} {cY : Y → Colors} (e : X ≃ Y) (h : cX = cY ∘ e)
(i : IndexValue d cX) : (mapIsoFiber d e h) (basisColorFiber cX i)
= basisColorFiber cY (indexValueIso d e h i) := by
lemma mapIsoFiber_basis {cX : X → Color} {cY : Y → Color} (e : X ≃ Y) (h : cX = cY ∘ e)
(i : IndexValue d cX) : (mapIso e h) (basis cX i)
= basis cY (indexValueIso d e h i) := by
funext a
rw [mapIsoFiber_apply]
rw [mapIso_apply]
by_cases ha : a = ((indexValueIso d e h) i)
· subst ha
nth_rewrite 2 [indexValueIso_eq_symm]
rw [Equiv.apply_symm_apply]
simp only [basisColorFiber]
simp only [basis]
erw [Pi.basisFun_apply, Pi.basisFun_apply]
simp only [stdBasis_same]
· simp only [basisColorFiber]
· simp only [basis]
erw [Pi.basisFun_apply, Pi.basisFun_apply]
simp
rw [if_neg, if_neg]
@ -851,24 +531,7 @@ lemma mapIsoFiber_basis {cX : X → Colors} {cY : Y → Colors} (e : X ≃ Y) (h
exact fun a_1 => ha (_root_.id (Eq.symm a_1))
end basis
/-!
## Contraction of indices
-/
open Marked
/-- The contraction of the marked indices in a tensor with two marked indices. -/
def contr {X : Type} (T : Marked d X 2) (h : T.markedColor 0 = τ (T.markedColor 1)) :
RealLorentzTensor d X where
color := T.unmarkedColor
coord := fun i =>
∑ x, T.coord (splitIndexValue.symm (i, T.twoMarkedIndexValue x $ colorsIndexDualCast h x))
/-! TODO: Following the ethos of modular operads, prove properties of contraction. -/

2
HepLean/SpaceTime/LorentzTensor/Real/Constructors.lean
View file

@ -29,7 +29,7 @@ to the real numbers, i.e. which is invariant under transformations of mapIso.
/-- An equivalence from Real tensors on an empty set to `ℝ`. -/
@[simps!]
def toReal (d : ℕ) {X : Type} (h : IsEmpty X) : RealLorentzTensor d X ≃ ℝ where
def toReal (d : ℕ) {X : Type} (h : IsEmpty X) (f : X → Color) : RealLorentzTensor d f ≃ ℝ where
toFun := fun T => T.coord (IsEmpty.elim h)
invFun := fun r => {
color := fun x => IsEmpty.elim h x,

119
HepLean/SpaceTime/LorentzTensor/Real/Contraction.lean Normal file
View file

@ -0,0 +1,119 @@
/-
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joseph Tooby-Smith
-/
import HepLean.SpaceTime.LorentzTensor.Real.Basic
import HepLean.SpaceTime.LorentzTensor.Real.TensorProducts
/-!
# Multiplication of Real Lorentz Tensors along an index
We define the multiplication of two singularly marked Lorentz tensors along the
marked index. This is equivalent to contracting two Lorentz tensors.
We prove various results about this multiplication.
-/
/-! TODO: Set up a good notation for the multiplication. -/
namespace RealLorentzTensor
open TensorProduct
open Set LinearMap Submodule
variable {d : ℕ} {X Y Y' X' : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
[Fintype Y'] [DecidableEq Y'] [Fintype X'] [DecidableEq X']
(cX : X → Color) (cY : Y → Color)
/-- The contraction of all indices of two tensors with dual index-colors.
This is a bilinear map to ℝ. -/
@[simps!]
def contrAll {f1 : X → Color} {f2 : Y → Color} (e : X ≃ Y) (hc : f1 = τ ∘ f2 ∘ e) :
RealLorentzTensor d f1 →ₗ[ℝ] RealLorentzTensor d f2 →ₗ[ℝ] ℝ where
toFun T := {
toFun := fun S => ∑ i, T i * S (indexValueDualIso d e hc i),
map_add' := fun S F => by
trans ∑ i, (T i * S (indexValueDualIso d e hc i) + T i * F (indexValueDualIso d e hc i))
exact Finset.sum_congr rfl (fun i _ => mul_add _ _ _ )
exact Finset.sum_add_distrib,
map_smul' := fun r S => by
trans ∑ i , r * (T i * S (indexValueDualIso d e hc i))
refine Finset.sum_congr rfl (fun x _ => ?_)
ring_nf
rw [mul_assoc]
rfl
rw [← Finset.mul_sum]
rfl}
map_add' := fun T S => by
ext F
trans ∑ i , (T i * F (indexValueDualIso d e hc i) + S i * F (indexValueDualIso d e hc i))
exact Finset.sum_congr rfl (fun x _ => add_mul _ _ _)
exact Finset.sum_add_distrib
map_smul' := fun r T => by
ext S
trans ∑ i , r * (T i * S (indexValueDualIso d e hc i))
refine Finset.sum_congr rfl (fun x _ => mul_assoc _ _ _)
rw [← Finset.mul_sum]
rfl
lemma contrAll_symm {f1 : X → Color} {f2 : Y → Color} (e : X ≃ Y)
(h : f1 = τ ∘ f2 ∘ e) (T : RealLorentzTensor d f1) (S : RealLorentzTensor d f2) :
contrAll e h T S = contrAll e.symm (indexValueDualIso_cond_symm h) S T := by
rw [contrAll_apply_apply, contrAll_apply_apply, ← Equiv.sum_comp (indexValueDualIso d e h)]
refine Finset.sum_congr rfl (fun i _ => ?_)
rw [mul_comm, ← Equiv.trans_apply]
simp
lemma contrAll_mapIsoFiber_right {f1 : X → Color} {f2 : Y → Color}
{g2 : Y' → Color} (e : X ≃ Y) (eY : Y ≃ Y')
(h : f1 = τ ∘ f2 ∘ e) (hY : f2 = g2 ∘ eY) (T : RealLorentzTensor d f1) (S : RealLorentzTensor d f2) :
contrAll e h T S = contrAll (e.trans eY) (indexValueDualIso_cond_trans_indexValueIso h hY)
T (mapIso eY hY S) := by
rw [contrAll_apply_apply, contrAll_apply_apply]
refine Finset.sum_congr rfl (fun i _ => Mathlib.Tactic.Ring.mul_congr rfl ?_ rfl)
rw [mapIso_apply, ← Equiv.trans_apply]
simp only [indexValueDualIso_trans_indexValueIso]
congr
ext1 x
simp only [Equiv.trans_apply, Equiv.symm_apply_apply]
lemma contrAll_mapIsoFiber_left {f1 : X → Color} {f2 : Y → Color}
{g1 : X' → Color} (e : X ≃ Y) (eX : X ≃ X')
(h : f1 = τ ∘ f2 ∘ e) (hX : f1 = g1 ∘ eX) (T : RealLorentzTensor d f1) (S : RealLorentzTensor d f2) :
contrAll e h T S = contrAll (eX.symm.trans e)
(indexValueIso_trans_indexValueDualIso_cond ((Equiv.eq_comp_symm eX g1 f1).mpr hX.symm) h)
(mapIso eX hX T) S := by
rw [contrAll_symm, contrAll_mapIsoFiber_right _ eX _ hX, contrAll_symm]
rfl
lemma contrAll_lorentzAction {f1 : X → Color} {f2 : Y → Color} (e : X ≃ Y)
(hc : f1 = τ ∘ f2 ∘ e) (T : RealLorentzTensor d f1) (S : RealLorentzTensor d f2) (Λ : LorentzGroup d) :
contrAll e hc (Λ • T) (Λ • S) = contrAll e hc T S := by
change ∑ i, (∑ j, toTensorRepMat Λ i j * T j) *
(∑ k, toTensorRepMat Λ (indexValueDualIso d e hc i) k * S k) = _
trans ∑ i, ∑ j, ∑ k, (toTensorRepMat Λ (indexValueDualIso d e hc i) k * toTensorRepMat Λ i j)
* T j * S k
· apply Finset.sum_congr rfl (fun x _ => ?_)
rw [Finset.sum_mul_sum]
apply Finset.sum_congr rfl (fun j _ => ?_)
apply Finset.sum_congr rfl (fun k _ => ?_)
ring
rw [Finset.sum_comm]
trans ∑ j, ∑ k, ∑ i, (toTensorRepMat Λ (indexValueDualIso d e hc i) k
* toTensorRepMat Λ i j) * T j * S k
· apply Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.sum_comm]
trans ∑ j, ∑ k, (toTensorRepMat 1 (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) k) j) * T j * S k
· apply Finset.sum_congr rfl (fun j _ => Finset.sum_congr rfl (fun k _ => ?_))
rw [← Finset.sum_mul, ← Finset.sum_mul]
erw [toTensorRepMat_indexValueDualIso_sum]
rw [Finset.sum_comm]
trans ∑ k, T (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) k) * S k
· apply Finset.sum_congr rfl (fun k _ => ?_)
rw [← Finset.sum_mul, ← toTensorRepMat_one_coord_sum' T]
rw [← Equiv.sum_comp (indexValueDualIso d e hc), ← indexValueDualIso_symm e hc]
simp only [Equiv.symm_apply_apply, contrAll_apply_apply]
end RealLorentzTensor

296
HepLean/SpaceTime/LorentzTensor/Real/LorentzAction.lean
View file

@ -19,15 +19,15 @@ The Lorentz action is currently only defined for finite and decidable types `X`.
namespace RealLorentzTensor
variable {d : ℕ} {X Y : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
(T : RealLorentzTensor d X) (c : X → Colors) (Λ Λ' : LorentzGroup d) {μ : Colors}
(c : X → Color) (Λ Λ' : LorentzGroup d) {μ : Color}
open LorentzGroup BigOperators Marked
open LorentzGroup BigOperators
/-- Monoid homomorphism from the Lorentz group to matrices indexed by `ColorsIndex d μ` for a
color `μ`.
This can be thought of as the representation of the Lorentz group for that color index. -/
def colorMatrix (μ : Colors) : LorentzGroup d →* Matrix (ColorsIndex d μ) (ColorsIndex d μ) ℝ where
def colorMatrix (μ : Color) : LorentzGroup d →* Matrix (ColorIndex d μ) (ColorIndex d μ) ℝ where
toFun Λ := match μ with
| .up => fun i j => Λ.1 i j
| .down => fun i j => (LorentzGroup.transpose Λ⁻¹).1 i j
@ -35,11 +35,11 @@ def colorMatrix (μ : Colors) : LorentzGroup d →* Matrix (ColorsIndex d μ) (C
ext i j
match μ with
| .up =>
simp only [lorentzGroupIsGroup_one_coe, OfNat.ofNat, One.one, ColorsIndex]
simp only [lorentzGroupIsGroup_one_coe, OfNat.ofNat, One.one, ColorIndex]
congr
| .down =>
simp only [transpose, inv_one, lorentzGroupIsGroup_one_coe, Matrix.transpose_one]
simp only [OfNat.ofNat, One.one, ColorsIndex]
simp only [OfNat.ofNat, One.one, ColorIndex]
congr
map_mul' Λ Λ' := by
ext i j
@ -51,18 +51,18 @@ def colorMatrix (μ : Colors) : LorentzGroup d →* Matrix (ColorsIndex d μ) (C
Matrix.transpose_mul, Matrix.transpose_apply]
rfl
lemma colorMatrix_ext {μ : Colors} {a b c d : ColorsIndex d μ} (hab : a = b) (hcd : c = d) :
lemma colorMatrix_ext {μ : Color} {a b c d : ColorIndex d μ} (hab : a = b) (hcd : c = d) :
(colorMatrix μ) Λ a c = (colorMatrix μ) Λ b d := by
rw [hab, hcd]
lemma colorMatrix_cast {μ ν : Colors} (h : μ = ν) (Λ : LorentzGroup d) :
lemma colorMatrix_cast {μ ν : Color} (h : μ = ν) (Λ : LorentzGroup d) :
colorMatrix ν Λ =
Matrix.reindex (colorsIndexCast h) (colorsIndexCast h) (colorMatrix μ Λ) := by
Matrix.reindex (colorIndexCast h) (colorIndexCast h) (colorMatrix μ Λ) := by
subst h
rfl
lemma colorMatrix_dual_cast {μ ν : Colors} (Λ : LorentzGroup d) (h : μ = τ ν) :
colorMatrix ν Λ = Matrix.reindex (colorsIndexDualCast h) (colorsIndexDualCast h)
lemma colorMatrix_dual_cast {μ ν : Color} (Λ : LorentzGroup d) (h : μ = τ ν) :
colorMatrix ν Λ = Matrix.reindex (colorIndexDualCast h) (colorIndexDualCast h)
(colorMatrix μ (LorentzGroup.transpose Λ⁻¹)) := by
subst h
match ν with
@ -70,16 +70,16 @@ lemma colorMatrix_dual_cast {μ ν : Colors} (Λ : LorentzGroup d) (h : μ = τ
ext i j
simp only [colorMatrix, MonoidHom.coe_mk, OneHom.coe_mk, τ, transpose, lorentzGroupIsGroup_inv,
Matrix.transpose_apply, minkowskiMetric.dual_transpose, minkowskiMetric.dual_dual,
Matrix.reindex_apply, colorsIndexDualCast_symm, Matrix.submatrix_apply]
Matrix.reindex_apply, colorIndexDualCast_symm, Matrix.submatrix_apply]
rfl
| .down =>
ext i j
simp only [τ, colorMatrix, MonoidHom.coe_mk, OneHom.coe_mk, colorsIndexDualCastSelf, transpose,
simp only [τ, colorMatrix, MonoidHom.coe_mk, OneHom.coe_mk, colorIndexDualCastSelf, transpose,
lorentzGroupIsGroup_inv, Matrix.transpose_apply, minkowskiMetric.dual_transpose,
minkowskiMetric.dual_dual, Matrix.reindex_apply, Equiv.coe_fn_symm_mk, Matrix.submatrix_apply]
rfl
lemma colorMatrix_transpose {μ : Colors} (Λ : LorentzGroup d) :
lemma colorMatrix_transpose {μ : Color} (Λ : LorentzGroup d) :
colorMatrix μ (LorentzGroup.transpose Λ) = (colorMatrix μ Λ).transpose := by
match μ with
| .up => rfl
@ -96,7 +96,7 @@ lemma colorMatrix_transpose {μ : Colors} (Λ : LorentzGroup d) :
/-- The matrix representation of the Lorentz group given a color of index. -/
@[simps!]
def toTensorRepMat {c : X → Colors} :
def toTensorRepMat {c : X → Color} :
LorentzGroup d →* Matrix (IndexValue d c) (IndexValue d c) ℝ where
toFun Λ := fun i j => ∏ x, colorMatrix (c x) Λ (i x) (j x)
map_one' := by
@ -135,18 +135,18 @@ lemma toTensorRepMat_mul' (i j : IndexValue d c) :
rw [Finset.prod_mul_distrib]
rfl
lemma toTensorRepMat_of_indexValueSumEquiv {cX : X → Colors} {cY : Y → Colors}
lemma toTensorRepMat_of_indexValueSumEquiv {cX : X → Color} {cY : Y → Color}
(i j : IndexValue d (Sum.elim cX cY)) :
toTensorRepMat Λ i j = toTensorRepMat Λ (indexValueSumEquiv i).1 (indexValueSumEquiv j).1 *
toTensorRepMat Λ (indexValueSumEquiv i).2 (indexValueSumEquiv j).2 :=
toTensorRepMat Λ i j = toTensorRepMat Λ (indexValueTensorator i).1 (indexValueTensorator j).1 *
toTensorRepMat Λ (indexValueTensorator i).2 (indexValueTensorator j).2 :=
Fintype.prod_sum_type fun x => (colorMatrix (Sum.elim cX cY x)) Λ (i x) (j x)
lemma toTensorRepMat_of_indexValueSumEquiv' {cX : X → Colors} {cY : Y → Colors}
lemma toTensorRepMat_of_indexValueSumEquiv' {cX : X → Color} {cY : Y → Color}
(i j : IndexValue d cX) (k l : IndexValue d cY) :
toTensorRepMat Λ i j * toTensorRepMat Λ k l =
toTensorRepMat Λ (indexValueSumEquiv.symm (i, k)) (indexValueSumEquiv.symm (j, l)) :=
toTensorRepMat Λ (indexValueTensorator.symm (i, k)) (indexValueTensorator.symm (j, l)) :=
(Fintype.prod_sum_type fun x => (colorMatrix (Sum.elim cX cY x)) Λ
(indexValueSumEquiv.symm (i, k) x) (indexValueSumEquiv.symm (j, l) x)).symm
(indexValueTensorator.symm (i, k) x) (indexValueTensorator.symm (j, l) x)).symm
/-!
@ -154,7 +154,7 @@ lemma toTensorRepMat_of_indexValueSumEquiv' {cX : X → Colors} {cY : Y → Colo
-/
lemma toTensorRepMat_indexValueDualIso_left {f1 : X → Colors} {f2 : Y → Colors}
lemma toTensorRepMat_indexValueDualIso_left {f1 : X → Color} {f2 : Y → Color}
(e : X ≃ Y) (hc : f1 = τ ∘ f2 ∘ e) (i : IndexValue d f1) (j : IndexValue d f2) :
toTensorRepMat Λ (indexValueDualIso d e hc i) j =
toTensorRepMat Λ⁻¹ (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) j) i := by
@ -162,18 +162,18 @@ lemma toTensorRepMat_indexValueDualIso_left {f1 : X → Colors} {f2 : Y → Colo
apply Finset.prod_congr rfl (fun x _ => ?_)
erw [colorMatrix_dual_cast Λ (congrFun hc x)]
rw [Matrix.reindex_apply, colorMatrix_transpose]
simp only [Function.comp_apply, colorsIndexDualCast_symm,
simp only [Function.comp_apply, colorIndexDualCast_symm,
Matrix.submatrix_apply, Matrix.transpose_apply]
rw [indexValueDualIso_eq_symm, indexValueDualIso_symm_apply',
indexValueDualIso_eq_symm, indexValueDualIso_symm_apply']
rw [← Equiv.trans_apply, colorsIndexDualCast_symm, colorsIndexDualCast_trans]
rw [← Equiv.trans_apply, colorIndexDualCast_symm, colorsIndexDualCast_trans]
apply colorMatrix_ext
simp
simp [colorsIndexCast]
simp [colorIndexCast]
apply cast_eq_iff_heq.mpr
rw [Equiv.symm_apply_apply]
lemma toTensorRepMat_indexValueDualIso_sum {f1 : X → Colors} {f2 : Y → Colors}
lemma toTensorRepMat_indexValueDualIso_sum {f1 : X → Color} {f2 : Y → Color}
(e : X ≃ Y) (hc : f1 = τ ∘ f2 ∘ e) (j : IndexValue d f1) (k : IndexValue d f2) :
(∑ i : IndexValue d f1, toTensorRepMat Λ ((indexValueDualIso d e hc) i) k * toTensorRepMat Λ i j) =
toTensorRepMat 1 (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) k) j := by
@ -183,8 +183,8 @@ lemma toTensorRepMat_indexValueDualIso_sum {f1 : X → Colors} {f2 : Y → Color
rw [toTensorRepMat_indexValueDualIso_left]
rw [← Matrix.mul_apply, ← toTensorRepMat.map_mul, inv_mul_self Λ]
lemma toTensorRepMat_one_coord_sum' {f1 : X → Colors}
(T : ColorFiber d f1) (k : IndexValue d f1) :
lemma toTensorRepMat_one_coord_sum' {f1 : X → Color}
(T : RealLorentzTensor d f1) (k : IndexValue d f1) :
∑ j, (toTensorRepMat 1 k j) * T j = T k := by
erw [Finset.sum_eq_single_of_mem k]
simp only [IndexValue, map_one, Matrix.one_apply_eq, one_mul]
@ -193,23 +193,6 @@ lemma toTensorRepMat_one_coord_sum' {f1 : X → Colors}
simp only [IndexValue, map_one, mul_eq_zero]
exact Or.inl (Matrix.one_apply_ne' hjk)
lemma toTensorRepMat_of_splitIndexValue' (T : Marked d X n)
(i j : T.UnmarkedIndexValue) (k l : T.MarkedIndexValue) :
toTensorRepMat Λ i j * toTensorRepMat Λ k l =
toTensorRepMat Λ (splitIndexValue.symm (i, k)) (splitIndexValue.symm (j, l)) :=
(Fintype.prod_sum_type fun x =>
(colorMatrix (T.color x)) Λ (splitIndexValue.symm (i, k) x) (splitIndexValue.symm (j, l) x)).symm
lemma toTensorRepMat_one_coord_sum (T : Marked d X n) (i : T.UnmarkedIndexValue)
(k : T.MarkedIndexValue) : T.coord (splitIndexValue.symm (i, k)) = ∑ j, toTensorRepMat 1 k j *
T.coord (splitIndexValue.symm (i, j)) := by
erw [Finset.sum_eq_single_of_mem k]
simp only [IndexValue, map_one, Matrix.one_apply_eq, one_mul]
exact Finset.mem_univ k
intro j _ hjk
simp [hjk, IndexValue]
exact Or.inl (Matrix.one_apply_ne' hjk)
/-!
@ -217,8 +200,8 @@ lemma toTensorRepMat_one_coord_sum (T : Marked d X n) (i : T.UnmarkedIndexValue)
-/
@[simps!]
def lorentzActionFiber {c : X → Colors} :
Representation ℝ (LorentzGroup d) (ColorFiber d c) where
def lorentzAction {c : X → Color} :
Representation ℝ (LorentzGroup d) (RealLorentzTensor d c) where
toFun Λ := {
toFun := fun T i => ∑ j, toTensorRepMat Λ i j * T j,
map_add' := fun T S => by
@ -260,13 +243,14 @@ def lorentzActionFiber {c : X → Colors} :
rw [← mul_assoc, Finset.prod_mul_distrib]
rfl
scoped[RealLorentzTensor] infixl:78 " • " => lorentzAction
/-- The Lorentz action commutes with `mapIso`. -/
lemma lorentzActionFiber_mapIsoFiber (e : X ≃ Y) {f1 : X → Colors}
{f2 : Y → Colors} (h : f1 = f2 ∘ e) (Λ : LorentzGroup d)
(T : ColorFiber d f1) : mapIsoFiber d e h (lorentzActionFiber Λ T) =
lorentzActionFiber Λ (mapIsoFiber d e h T) := by
lemma lorentzAction_mapIso (e : X ≃ Y) {f1 : X → Color}
{f2 : Y → Color} (h : f1 = f2 ∘ e) (Λ : LorentzGroup d)
(T : RealLorentzTensor d f1) : mapIso e h (Λ • T) = Λ • (mapIso e h T) := by
funext i
rw [mapIsoFiber_apply, lorentzActionFiber_apply_apply, lorentzActionFiber_apply_apply]
rw [mapIso_apply, lorentzAction_apply_apply, lorentzAction_apply_apply]
rw [← Equiv.sum_comp (indexValueIso d e h)]
refine Finset.sum_congr rfl (fun j _ => Mathlib.Tactic.Ring.mul_congr ?_ ?_ rfl)
· rw [← Equiv.prod_comp e]
@ -277,236 +261,48 @@ lemma lorentzActionFiber_mapIsoFiber (e : X ≃ Y) {f1 : X → Colors}
apply colorMatrix_ext
rw [indexValueIso_eq_symm, indexValueIso_symm_apply']
erw [← Equiv.eq_symm_apply]
simp only [Function.comp_apply, Equiv.symm_symm_apply, colorsIndexCast, Equiv.cast_symm,
simp only [Function.comp_apply, Equiv.symm_symm_apply, colorIndexCast, Equiv.cast_symm,
Equiv.cast_apply, cast_cast, cast_eq]
rw [indexValueIso_eq_symm, indexValueIso_symm_apply']
simp [colorsIndexCast]
simp [colorIndexCast]
symm
refine cast_eq_iff_heq.mpr ?_
rw [Equiv.symm_apply_apply]
· rw [mapIsoFiber_apply]
· rw [mapIso_apply]
apply congrArg
rw [← Equiv.trans_apply]
simp
/-- Action of the Lorentz group on `X`-indexed Real Lorentz Tensors. -/
@[simps!]
instance lorentzAction : MulAction (LorentzGroup d) (RealLorentzTensor d X) where
smul Λ T := ⟨T.color, lorentzActionFiber Λ T.coord⟩
one_smul T := by
refine ext rfl ?_
simp only [HSMul.hSMul, map_one, LinearMap.one_apply]
rfl
mul_smul Λ Λ' T := by
refine ext rfl ?_
simp [HSMul.hSMul]
rfl
lemma lorentzAction_smul_coord' {d : ℕ} {X : Type} [Fintype X] [DecidableEq X] (Λ : ↑(𝓛 d))
(T : RealLorentzTensor d X) (i : IndexValue d T.color) :
(Λ • T).coord i = ∑ j : IndexValue d T.color, toTensorRepMat Λ i j * T.coord j := by
rfl
/-!
## Properties of the Lorentz action.
-/
/-- The action on an empty Lorentz tensor is trivial. -/
lemma lorentzAction_on_isEmpty [IsEmpty X] (Λ : LorentzGroup d) (T : RealLorentzTensor d X) :
Λ • T = T := by
refine ext rfl ?_
funext i
erw [lorentzAction_smul_coord, mapIsoFiber_apply]
simp only [lorentzActionFiber_apply_apply, Finset.univ_eq_empty, Finset.prod_empty, one_mul,
indexValueIso_refl, Equiv.refl_symm]
simp only [IndexValue, Unique.eq_default, Finset.univ_unique, Finset.sum_const,
Finset.card_singleton, one_smul]
/-- The Lorentz action commutes with `mapIso`. -/
lemma lorentzAction_mapIso (f : X ≃ Y) (Λ : LorentzGroup d) (T : RealLorentzTensor d X) :
mapIso d f (Λ • T) = Λ • (mapIso d f T) :=
ext rfl (lorentzActionFiber_mapIsoFiber f _ Λ T.coord)
section
variable {d : ℕ} {X Y Y' X' : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
[Fintype Y'] [DecidableEq Y'] [Fintype X'] [DecidableEq X']
(cX : X → Colors) (cY : Y → Colors)
(cX : X → Color) (cY : Y → Color)
lemma lorentzActionFiber_basis (Λ : LorentzGroup d) (i : IndexValue d cX) :
lorentzActionFiber Λ (basisColorFiber cX i) =
∑ j, toTensorRepMat Λ j i • basisColorFiber cX j := by
lemma lorentzAction_basis (Λ : LorentzGroup d) (i : IndexValue d cX) :
Λ • (basis cX i) = ∑ j, toTensorRepMat Λ j i • basis cX j := by
funext k
simp only [lorentzActionFiber, MonoidHom.coe_mk, OneHom.coe_mk,
simp only [lorentzAction, MonoidHom.coe_mk, OneHom.coe_mk,
LinearMap.coe_mk, AddHom.coe_mk]
rw [Finset.sum_apply]
rw [Finset.sum_eq_single_of_mem i, Finset.sum_eq_single_of_mem k]
change _ = toTensorRepMat Λ k i * (Pi.basisFun ℝ (IndexValue d cX)) k k
rw [basisColorFiber]
rw [basis]
erw [Pi.basisFun_apply, Pi.basisFun_apply]
simp
exact Finset.mem_univ k
intro b _ hbk
change toTensorRepMat Λ b i • (basisColorFiber cX) b k = 0
erw [basisColorFiber, Pi.basisFun_apply]
change toTensorRepMat Λ b i • (basis cX) b k = 0
erw [basis, Pi.basisFun_apply]
simp [hbk]
exact Finset.mem_univ i
intro b hb hbk
erw [basisColorFiber, Pi.basisFun_apply]
erw [basis, Pi.basisFun_apply]
simp [hbk]
intro a
subst a
simp_all only [Finset.mem_univ, ne_eq, not_true_eq_false]
end
/-!
## The Lorentz action on marked tensors.
-/
@[simps!]
instance : MulAction (LorentzGroup d) (Marked d X n) := lorentzAction
/-- Action of the Lorentz group on just marked indices. -/
@[simps!]
def markedLorentzAction : MulAction (LorentzGroup d) (Marked d X n) where
smul Λ T := {
color := T.color,
coord := fun i => ∑ j, toTensorRepMat Λ (splitIndexValue i).2 j *
T.coord (splitIndexValue.symm ((splitIndexValue i).1, j))}
one_smul T := by
refine ext rfl ?_
funext i
simp only [HSMul.hSMul, map_one]
erw [Finset.sum_eq_single_of_mem (splitIndexValue i).2]
erw [Matrix.one_apply_eq (splitIndexValue i).2]
simp only [IndexValue, one_mul, indexValueIso_refl, Equiv.refl_apply]
apply congrArg
exact Equiv.symm_apply_apply splitIndexValue i
exact Finset.mem_univ (splitIndexValue i).2
exact fun j _ hij => mul_eq_zero.mpr (Or.inl (Matrix.one_apply_ne' hij))
mul_smul Λ Λ' T := by
refine ext rfl ?_
simp only [HSMul.hSMul]
funext i
have h1 : ∑ (j : T.MarkedIndexValue), toTensorRepMat (Λ * Λ') (splitIndexValue i).2 j
* T.coord (splitIndexValue.symm ((splitIndexValue i).1, j)) =
∑ (j : T.MarkedIndexValue), ∑ (k : T.MarkedIndexValue),
(∏ x, ((colorMatrix (T.markedColor x) Λ ((splitIndexValue i).2 x) (k x)) *
(colorMatrix (T.markedColor x) Λ' (k x) (j x)))) *
T.coord (splitIndexValue.symm ((splitIndexValue i).1, j)) := by
refine Finset.sum_congr rfl (fun j _ => ?_)
rw [toTensorRepMat_mul', Finset.sum_mul]
rfl
erw [h1]
rw [Finset.sum_comm]
refine Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.mul_sum]
refine Finset.sum_congr rfl (fun k _ => ?_)
simp only [toTensorRepMat, IndexValue]
rw [← mul_assoc]
congr
rw [Finset.prod_mul_distrib]
rfl
/-- Action of the Lorentz group on just unmarked indices. -/
@[simps!]
def unmarkedLorentzAction : MulAction (LorentzGroup d) (Marked d X n) where
smul Λ T := {
color := T.color,
coord := fun i => ∑ j, toTensorRepMat Λ (splitIndexValue i).1 j *
T.coord (splitIndexValue.symm (j, (splitIndexValue i).2))}
one_smul T := by
refine ext rfl ?_
funext i
simp only [HSMul.hSMul, map_one]
erw [Finset.sum_eq_single_of_mem (splitIndexValue i).1]
erw [Matrix.one_apply_eq (splitIndexValue i).1]
simp only [IndexValue, one_mul, indexValueIso_refl, Equiv.refl_apply]
apply congrArg
exact Equiv.symm_apply_apply splitIndexValue i
exact Finset.mem_univ (splitIndexValue i).1
exact fun j _ hij => mul_eq_zero.mpr (Or.inl (Matrix.one_apply_ne' hij))
mul_smul Λ Λ' T := by
refine ext rfl ?_
simp only [HSMul.hSMul]
funext i
have h1 : ∑ (j : T.UnmarkedIndexValue), toTensorRepMat (Λ * Λ') (splitIndexValue i).1 j
* T.coord (splitIndexValue.symm (j, (splitIndexValue i).2)) =
∑ (j : T.UnmarkedIndexValue), ∑ (k : T.UnmarkedIndexValue),
(∏ x, ((colorMatrix (T.unmarkedColor x) Λ ((splitIndexValue i).1 x) (k x)) *
(colorMatrix (T.unmarkedColor x) Λ' (k x) (j x)))) *
T.coord (splitIndexValue.symm (j, (splitIndexValue i).2)) := by
refine Finset.sum_congr rfl (fun j _ => ?_)
rw [toTensorRepMat_mul', Finset.sum_mul]
rfl
erw [h1]
rw [Finset.sum_comm]
refine Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.mul_sum]
refine Finset.sum_congr rfl (fun k _ => ?_)
simp only [toTensorRepMat, IndexValue]
rw [← mul_assoc]
congr
rw [Finset.prod_mul_distrib]
rfl
/-- Notation for `markedLorentzAction.smul`. -/
scoped[RealLorentzTensor] infixr:73 " •ₘ " => markedLorentzAction.smul
/-- Notation for `unmarkedLorentzAction.smul`. -/
scoped[RealLorentzTensor] infixr:73 " •ᵤₘ " => unmarkedLorentzAction.smul
/-- Acting on unmarked and then marked indices is equivalent to acting on all indices. -/
lemma marked_unmarked_action_eq_action (T : Marked d X n) : Λ •ₘ (Λ •ᵤₘ T) = Λ • T := by
refine ext rfl ?_
funext i
change ∑ j, toTensorRepMat Λ (splitIndexValue i).2 j *
(∑ k, toTensorRepMat Λ (splitIndexValue i).1 k * T.coord (splitIndexValue.symm (k, j))) = _
trans ∑ j, ∑ k, (toTensorRepMat Λ (splitIndexValue i).2 j *
toTensorRepMat Λ (splitIndexValue i).1 k) * T.coord (splitIndexValue.symm (k, j))
apply Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.mul_sum]
apply Finset.sum_congr rfl (fun k _ => ?_)
exact Eq.symm (mul_assoc _ _ _)
trans ∑ j, ∑ k, (toTensorRepMat Λ i (splitIndexValue.symm (k, j))
* T.coord (splitIndexValue.symm (k, j)))
apply Finset.sum_congr rfl (fun j _ => (Finset.sum_congr rfl (fun k _ => ?_)))
rw [mul_comm (toTensorRepMat _ _ _), toTensorRepMat_of_splitIndexValue']
simp only [IndexValue, Finset.mem_univ, Prod.mk.eta, Equiv.symm_apply_apply]
trans ∑ p, (toTensorRepMat Λ i p * T.coord p)
rw [← Equiv.sum_comp splitIndexValue.symm, Fintype.sum_prod_type, Finset.sum_comm]
rfl
rfl
/-- Acting on marked and then unmarked indices is equivalent to acting on all indices. -/
lemma unmarked_marked_action_eq_action (T : Marked d X n) : Λ •ᵤₘ (Λ •ₘ T) = Λ • T := by
refine ext rfl ?_
funext i
change ∑ j, toTensorRepMat Λ (splitIndexValue i).1 j *
(∑ k, toTensorRepMat Λ (splitIndexValue i).2 k * T.coord (splitIndexValue.symm (j, k))) = _
trans ∑ j, ∑ k, (toTensorRepMat Λ (splitIndexValue i).1 j *
toTensorRepMat Λ (splitIndexValue i).2 k) * T.coord (splitIndexValue.symm (j, k))
apply Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.mul_sum]
apply Finset.sum_congr rfl (fun k _ => ?_)
exact Eq.symm (mul_assoc _ _ _)
trans ∑ j, ∑ k, (toTensorRepMat Λ i (splitIndexValue.symm (j, k))
* T.coord (splitIndexValue.symm (j, k)))
apply Finset.sum_congr rfl (fun j _ => (Finset.sum_congr rfl (fun k _ => ?_)))
rw [toTensorRepMat_of_splitIndexValue']
simp only [IndexValue, Finset.mem_univ, Prod.mk.eta, Equiv.symm_apply_apply]
trans ∑ p, (toTensorRepMat Λ i p * T.coord p)
rw [← Equiv.sum_comp splitIndexValue.symm, Fintype.sum_prod_type]
rfl
rfl
/-- The marked and unmarked actions commute. -/
lemma marked_unmarked_action_comm (T : Marked d X n) : Λ •ᵤₘ (Λ •ₘ T) = Λ •ₘ (Λ •ᵤₘ T) := by
rw [unmarked_marked_action_eq_action, marked_unmarked_action_eq_action]
/-! TODO: Show that the Lorentz action commutes with contraction. -/
/-! TODO: Show that the Lorentz action commutes with rising and lowering indices. -/
end RealLorentzTensor

534
HepLean/SpaceTime/LorentzTensor/Real/Multiplication.lean
View file

@ -1,534 +0,0 @@
/-
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joseph Tooby-Smith
-/
import HepLean.SpaceTime.LorentzTensor.Real.Basic
import HepLean.SpaceTime.LorentzTensor.Real.LorentzAction
/-!
# Multiplication of Real Lorentz Tensors along an index
We define the multiplication of two singularly marked Lorentz tensors along the
marked index. This is equivalent to contracting two Lorentz tensors.
We prove various results about this multiplication.
-/
/-! TODO: Set up a good notation for the multiplication. -/
namespace RealLorentzTensor
variable {d : ℕ} {X Y : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
(T : RealLorentzTensor d X) (c : X → Colors) (Λ Λ' : LorentzGroup d) {μ : Colors}
open Marked
section mulMarkedFiber
variable {cX : X → Colors} {cY : Y → Colors} {fX : Fin 1 → Colors} {fY : Fin 1 → Colors}
/-- The index value appearing in the multiplication of Marked tensors on the left. -/
def mulMarkedFiberFstArg (i : IndexValue d (Sum.elim cX cY)) (x : ColorsIndex d (fX 0)) :
IndexValue d (Sum.elim cX fX) :=
indexValueSumEquiv.symm ((indexValueSumEquiv i).1, indexValueFinOne x)
/-- The index value appearing in the multiplication of Marked tensors on the right. -/
def mulMarkedFiberSndArg (i : IndexValue d (Sum.elim cX cY)) (x : ColorsIndex d (fX 0))
(h : fX 0 = τ (fY 0)) : IndexValue d (Sum.elim cY fY) :=
indexValueSumEquiv.symm ((indexValueSumEquiv i).2, indexValueFinOne $ colorsIndexDualCast h x)
def mulMarkedFiber (h : fX 0 = τ (fY 0)) : ColorFiber d (Sum.elim cX fX) →ₗ[ℝ]
ColorFiber d (Sum.elim cY fY) →ₗ[ℝ] ColorFiber d (Sum.elim cX cY) where
toFun T := {
toFun := fun S i => ∑ x, T (mulMarkedFiberFstArg i x) * S (mulMarkedFiberSndArg i x h),
map_add' := fun F S => by
funext i
trans ∑ x , (T (mulMarkedFiberFstArg i x) * F (mulMarkedFiberSndArg i x h) +
T (mulMarkedFiberFstArg i x) * S (mulMarkedFiberSndArg i x h))
exact Finset.sum_congr rfl (fun x _ => mul_add _ _ _ )
exact Finset.sum_add_distrib,
map_smul' := fun r S => by
funext i
trans ∑ x , r * (T (mulMarkedFiberFstArg i x) * S (mulMarkedFiberSndArg i x h))
refine Finset.sum_congr rfl (fun x _ => ?_)
ring_nf
rw [mul_assoc]
rfl
rw [← Finset.mul_sum]
rfl}
map_add' := fun T S => by
ext F
funext i
trans ∑ x , (T (mulMarkedFiberFstArg i x) * F (mulMarkedFiberSndArg i x h) +
S (mulMarkedFiberFstArg i x) * F (mulMarkedFiberSndArg i x h))
exact Finset.sum_congr rfl (fun x _ => add_mul _ _ _)
exact Finset.sum_add_distrib
map_smul' := fun r T => by
ext S
funext i
trans ∑ x , r * (T (mulMarkedFiberFstArg i x) * S (mulMarkedFiberSndArg i x h))
refine Finset.sum_congr rfl (fun x _ => mul_assoc _ _ _)
rw [← Finset.mul_sum]
rfl
end mulMarkedFiber
/-- The contraction of the marked indices of two tensors each with one marked index, which
is dual to the others. The contraction is done via
`φ^μ ψ_μ = φ^0 ψ_0 + φ^1 ψ_1 + ...`. -/
@[simps!]
def mulMarked {X Y : Type} (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 0)) :
RealLorentzTensor d (X ⊕ Y) where
color := Sum.elim T.unmarkedColor S.unmarkedColor
coord := fun i => ∑ x,
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, oneMarkedIndexValue x)) *
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2,
oneMarkedIndexValue $ colorsIndexDualCast h x))
/-- The index value appearing in the multiplication of Marked tensors on the left. -/
def mulMarkedFstArg {X Y : Type} {T : Marked d X 1} {S : Marked d Y 1}
(i : IndexValue d (Sum.elim T.unmarkedColor S.unmarkedColor))
(x : ColorsIndex d (T.color (markedPoint X 0))) : IndexValue d T.color :=
splitIndexValue.symm ((indexValueSumEquiv i).1, oneMarkedIndexValue x)
lemma mulMarkedFstArg_inr {X Y : Type} {T : Marked d X 1} {S : Marked d Y 1}
(i : IndexValue d (Sum.elim T.unmarkedColor S.unmarkedColor))
(x : ColorsIndex d (T.color (markedPoint X 0))) :
mulMarkedFstArg i x (Sum.inr 0) = x := by
rfl
lemma mulMarkedFstArg_inl {X Y : Type} {T : Marked d X 1} {S : Marked d Y 1}
(i : IndexValue d (Sum.elim T.unmarkedColor S.unmarkedColor))
(x : ColorsIndex d (T.color (markedPoint X 0))) (c : X):
mulMarkedFstArg i x (Sum.inl c) = i (Sum.inl c) := by
rfl
/-- The index value appearing in the multiplication of Marked tensors on the right. -/
def mulMarkedSndArg {X Y : Type} {T : Marked d X 1} {S : Marked d Y 1}
(i : IndexValue d (Sum.elim T.unmarkedColor S.unmarkedColor))
(x : ColorsIndex d (T.color (markedPoint X 0))) (h : T.markedColor 0 = τ (S.markedColor 0)) :
IndexValue d S.color :=
splitIndexValue.symm ((indexValueSumEquiv i).2, oneMarkedIndexValue $ colorsIndexDualCast h x)
/-!
## Expressions for multiplication
-/
/-! TODO: Where appropriate write these expresions in terms of `indexValueDualIso`. -/
lemma mulMarked_colorsIndex_right {X Y : Type} (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 0)) :
(mulMarked T S h).coord = fun i => ∑ x,
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1,
oneMarkedIndexValue $ colorsIndexDualCast (color_eq_dual_symm h) x)) *
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, oneMarkedIndexValue x)) := by
funext i
rw [← Equiv.sum_comp (colorsIndexDualCast h)]
apply Finset.sum_congr rfl (fun x _ => ?_)
congr
rw [← colorsIndexDualCast_symm]
exact (Equiv.apply_eq_iff_eq_symm_apply (colorsIndexDualCast h)).mp rfl
lemma mulMarked_indexValue_left {X Y : Type} (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 0)) :
(mulMarked T S h).coord = fun i => ∑ j,
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, j)) *
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2,
(oneMarkedIndexValue $ (colorsIndexDualCast h) $ oneMarkedIndexValue.symm j))) := by
funext i
rw [← Equiv.sum_comp (oneMarkedIndexValue)]
rfl
lemma mulMarked_indexValue_right {X Y : Type} (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 0)) :
(mulMarked T S h).coord = fun i => ∑ j,
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1,
oneMarkedIndexValue $ (colorsIndexDualCast h).symm $ oneMarkedIndexValue.symm j)) *
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, j)) := by
funext i
rw [mulMarked_colorsIndex_right]
rw [← Equiv.sum_comp (oneMarkedIndexValue)]
apply Finset.sum_congr rfl (fun x _ => ?_)
congr
exact Eq.symm (colorsIndexDualCast_symm h)
/-!
## Properties of multiplication
-/
/-- Multiplication is well behaved with regard to swapping tensors. -/
lemma mulMarked_symm {X Y : Type} (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 0)) :
mapIso d (Equiv.sumComm X Y) (mulMarked T S h) = mulMarked S T (color_eq_dual_symm h) := by
refine ext ?_ ?_
· funext a
cases a with
| inl _ => rfl
| inr _ => rfl
· funext i
rw [mulMarked_colorsIndex_right]
refine Fintype.sum_congr _ _ (fun x => ?_)
rw [mul_comm]
rfl
/-- Multiplication commutes with `mapIso`. -/
lemma mulMarked_mapIso {X Y Z : Type} (T : Marked d X 1) (S : Marked d Y 1) (f : X ≃ W)
(g : Y ≃ Z) (h : T.markedColor 0 = τ (S.markedColor 0)) :
mapIso d (Equiv.sumCongr f g) (mulMarked T S h) = mulMarked (mapIso d (Equiv.sumCongr f (Equiv.refl _)) T)
(mapIso d (Equiv.sumCongr g (Equiv.refl _)) S) h := by
refine ext ?_ ?_
· funext a
cases a with
| inl _ => rfl
| inr _ => rfl
· funext i
rw [mapIso_apply_coord, mapIsoFiber_apply, mapIsoFiber_apply, mulMarked_coord, mulMarked_coord]
refine Fintype.sum_congr _ _ (fun x => ?_)
rw [mapIso_apply_coord, mapIso_apply_coord]
refine Mathlib.Tactic.Ring.mul_congr ?_ ?_ rfl
· apply congrArg
exact (Equiv.symm_apply_eq splitIndexValue).mpr rfl
· apply congrArg
exact (Equiv.symm_apply_eq splitIndexValue).mpr rfl
/-!
## Lorentz action and multiplication.
-/
/-- The marked Lorentz Action leaves multiplication invariant. -/
lemma mulMarked_markedLorentzAction (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 1)) :
mulMarked (Λ •ₘ T) (Λ •ₘ S) h = mulMarked T S h := by
refine ext rfl ?_
funext i
change ∑ x, (∑ j, toTensorRepMat Λ (oneMarkedIndexValue x) j *
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, j))) *
(∑ k, toTensorRepMat Λ (oneMarkedIndexValue $ colorsIndexDualCast h x) k *
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, k))) = _
trans ∑ x, ∑ j, ∑ k, (toTensorRepMat Λ (oneMarkedIndexValue $ colorsIndexDualCast h x) k
* toTensorRepMat Λ (oneMarkedIndexValue x) j) *
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, j))
* S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, k))
apply Finset.sum_congr rfl (fun x _ => ?_)
rw [Finset.sum_mul_sum]
apply Finset.sum_congr rfl (fun j _ => ?_)
apply Finset.sum_congr rfl (fun k _ => ?_)
ring
rw [Finset.sum_comm]
trans ∑ j, ∑ k, ∑ x, (toTensorRepMat Λ (oneMarkedIndexValue $ colorsIndexDualCast h x) k
* toTensorRepMat Λ (oneMarkedIndexValue x) j) *
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, j))
* S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, k))
apply Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.sum_comm]
trans ∑ j, ∑ k, (toTensorRepMat 1
(oneMarkedIndexValue $ (colorsIndexDualCast h).symm $ oneMarkedIndexValue.symm k) j) *
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, j))
* S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, k))
apply Finset.sum_congr rfl (fun j _ => Finset.sum_congr rfl (fun k _ => ?_))
rw [← Finset.sum_mul, ← Finset.sum_mul]
erw [toTensorRepMap_sum_dual]
rfl
rw [Finset.sum_comm]
trans ∑ k, T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1,
(oneMarkedIndexValue $ (colorsIndexDualCast h).symm $ oneMarkedIndexValue.symm k)))*
S.coord (splitIndexValue.symm ((indexValueSumEquiv i).2, k))
apply Finset.sum_congr rfl (fun k _ => ?_)
rw [← Finset.sum_mul, ← toTensorRepMat_one_coord_sum T]
rw [← Equiv.sum_comp (oneMarkedIndexValue)]
erw [← Equiv.sum_comp (colorsIndexDualCast h)]
simp
rfl
/-- The unmarked Lorentz Action commutes with multiplication. -/
lemma mulMarked_unmarkedLorentzAction (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 1)) :
mulMarked (Λ •ᵤₘ T) (Λ •ᵤₘ S) h = Λ • mulMarked T S h := by
refine ext rfl ?_
funext i
change ∑ x, (∑ j, toTensorRepMat Λ (indexValueSumEquiv i).1 j *
T.coord (splitIndexValue.symm (j, oneMarkedIndexValue x)))*
∑ k, toTensorRepMat Λ (indexValueSumEquiv i).2 k *
S.coord (splitIndexValue.symm (k, oneMarkedIndexValue $ colorsIndexDualCast h x)) = _
trans ∑ x, ∑ j, ∑ k, (toTensorRepMat Λ (indexValueSumEquiv i).1 j *
T.coord (splitIndexValue.symm (j, oneMarkedIndexValue x)))*
toTensorRepMat Λ (indexValueSumEquiv i).2 k *
S.coord (splitIndexValue.symm (k, oneMarkedIndexValue $ colorsIndexDualCast h x))
· apply Finset.sum_congr rfl (fun x _ => ?_)
rw [Finset.sum_mul_sum ]
apply Finset.sum_congr rfl (fun j _ => ?_)
apply Finset.sum_congr rfl (fun k _ => ?_)
ring
rw [Finset.sum_comm]
trans ∑ j, ∑ k, ∑ x, (toTensorRepMat Λ (indexValueSumEquiv i).1 j *
T.coord (splitIndexValue.symm (j, oneMarkedIndexValue x)))*
toTensorRepMat Λ (indexValueSumEquiv i).2 k *
S.coord (splitIndexValue.symm (k, oneMarkedIndexValue $ colorsIndexDualCast h x))
· exact Finset.sum_congr rfl (fun j _ => Finset.sum_comm)
trans ∑ j, ∑ k,
((toTensorRepMat Λ (indexValueSumEquiv i).1 j) * toTensorRepMat Λ (indexValueSumEquiv i).2 k)
* ∑ x, (T.coord (splitIndexValue.symm (j, oneMarkedIndexValue x)))
* S.coord (splitIndexValue.symm (k, oneMarkedIndexValue $ colorsIndexDualCast h x))
· apply Finset.sum_congr rfl (fun j _ => Finset.sum_congr rfl (fun k _ => ?_))
rw [Finset.mul_sum]
apply Finset.sum_congr rfl (fun x _ => ?_)
ring
trans ∑ j, ∑ k, toTensorRepMat Λ i (indexValueSumEquiv.symm (j, k)) *
∑ x, (T.coord (splitIndexValue.symm (j, oneMarkedIndexValue x)))
* S.coord (splitIndexValue.symm (k, oneMarkedIndexValue $ colorsIndexDualCast h x))
apply Finset.sum_congr rfl (fun j _ => Finset.sum_congr rfl (fun k _ => ?_))
· rw [toTensorRepMat_of_indexValueSumEquiv']
congr
simp only [IndexValue, Finset.mem_univ, Prod.mk.eta, Equiv.symm_apply_apply, mulMarked_color]
trans ∑ p, toTensorRepMat Λ i p *
∑ x, (T.coord (splitIndexValue.symm ((indexValueSumEquiv p).1, oneMarkedIndexValue x)))
* S.coord (splitIndexValue.symm ((indexValueSumEquiv p).2,
oneMarkedIndexValue $ colorsIndexDualCast h x))
· erw [← Equiv.sum_comp indexValueSumEquiv.symm]
exact Eq.symm Fintype.sum_prod_type
rfl
/-- The Lorentz action commutes with multiplication. -/
lemma mulMarked_lorentzAction (T : Marked d X 1) (S : Marked d Y 1)
(h : T.markedColor 0 = τ (S.markedColor 1)) :
mulMarked (Λ • T) (Λ • S) h = Λ • mulMarked T S h := by
simp only [← marked_unmarked_action_eq_action]
rw [mulMarked_markedLorentzAction, mulMarked_unmarkedLorentzAction]
/-!
## Multiplication on selected indices
-/
variable {n m : ℕ} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
{X' Y' Z : Type} [Fintype X'] [DecidableEq X'] [Fintype Y'] [DecidableEq Y']
[Fintype Z] [DecidableEq Z]
/-- The multiplication of two real Lorentz Tensors along specified indices. -/
@[simps!]
def mult (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y) (x : X) (y : Y)
(h : T.color x = τ (S.color y)) : RealLorentzTensor d ({x' // x' ≠ x} ⊕ {y' // y' ≠ y}) :=
mulMarked (markSingle x T) (markSingle y S) h
/-- The first index value appearing in the multiplication of two Lorentz tensors. -/
def multFstArg {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0))) :
IndexValue d T.color := (markSingleIndexValue T x).symm (mulMarkedFstArg i a)
lemma multFstArg_ext {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
{i j : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor)}
{a b : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0))}
(hij : i = j) (hab : a = b) : multFstArg i a = multFstArg j b := by
subst hij; subst hab
rfl
lemma multFstArg_on_mem {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0))) :
multFstArg i a x = a := by
rw [multFstArg, markSingleIndexValue]
simp only [ne_eq, Fintype.univ_ofSubsingleton, Fin.zero_eta, Fin.isValue, Equiv.symm_trans_apply,
Sum.map_inr, id_eq]
erw [markEmbeddingIndexValue_apply_symm_on_mem]
swap
simp only [Nat.succ_eq_add_one, Nat.reduceAdd, Finset.univ_unique, Fin.default_eq_zero,
Fin.isValue, Finset.image_singleton, embedSingleton_apply, Finset.mem_singleton]
rw [indexValueIso_symm_apply']
erw [Equiv.symm_apply_eq, Equiv.symm_apply_eq]
simp only [Function.comp_apply, colorsIndexCast, Equiv.cast_symm, Equiv.cast_apply, cast_cast]
symm
apply cast_eq_iff_heq.mpr
rw [embedSingleton_toEquivRange_symm]
rfl
lemma multFstArg_on_not_mem {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0)))
(c : X) (hc : c ≠ x) : multFstArg i a c = i (Sum.inl ⟨c, hc⟩) := by
rw [multFstArg, markSingleIndexValue]
simp only [ne_eq, Fintype.univ_ofSubsingleton, Fin.zero_eta, Fin.isValue, Equiv.symm_trans_apply,
Sum.map_inr, id_eq]
erw [markEmbeddingIndexValue_apply_symm_on_not_mem]
swap
simpa using hc
rfl
/-- The second index value appearing in the multiplication of two Lorentz tensors. -/
def multSndArg {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0)))
(h : T.color x = τ (S.color y)) : IndexValue d S.color :=
(markSingleIndexValue S y).symm (mulMarkedSndArg i a h)
lemma multSndArg_on_mem {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0)))
(h : T.color x = τ (S.color y)) : multSndArg i a h y = colorsIndexDualCast h a := by
rw [multSndArg, markSingleIndexValue]
simp only [ne_eq, Fintype.univ_ofSubsingleton, Fin.zero_eta, Fin.isValue, Equiv.symm_trans_apply,
Sum.map_inr, id_eq]
erw [markEmbeddingIndexValue_apply_symm_on_mem]
swap
simp only [Nat.succ_eq_add_one, Nat.reduceAdd, Finset.univ_unique, Fin.default_eq_zero,
Fin.isValue, Finset.image_singleton, embedSingleton_apply, Finset.mem_singleton]
rw [indexValueIso_symm_apply']
erw [Equiv.symm_apply_eq, Equiv.symm_apply_eq]
simp only [Function.comp_apply, colorsIndexCast, Equiv.cast_symm, Equiv.cast_apply, cast_cast]
symm
apply cast_eq_iff_heq.mpr
rw [embedSingleton_toEquivRange_symm]
rfl
lemma multSndArg_on_not_mem {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor))
(a : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0)))
(h : T.color x = τ (S.color y)) (c : Y) (hc : c ≠ y) :
multSndArg i a h c = i (Sum.inr ⟨c, hc⟩) := by
rw [multSndArg, markSingleIndexValue]
simp only [ne_eq, Fintype.univ_ofSubsingleton, Fin.zero_eta, Fin.isValue, Equiv.symm_trans_apply,
Sum.map_inr, id_eq]
erw [markEmbeddingIndexValue_apply_symm_on_not_mem]
swap
simpa using hc
rfl
lemma multSndArg_ext {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y} {x : X} {y : Y}
{i j : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor)}
{a b : ColorsIndex d ((markSingle x T).color (markedPoint {x' // x' ≠ x} 0))}
(h : T.color x = τ (S.color y)) (hij : i = j) (hab : a = b) :
multSndArg i a h = multSndArg j b h := by
subst hij
subst hab
rfl
lemma mult_coord_arg (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y) (x : X) (y : Y)
(h : T.color x = τ (S.color y))
(i : IndexValue d (Sum.elim (markSingle x T).unmarkedColor (markSingle y S).unmarkedColor)) :
(mult T S x y h).coord i = ∑ a, T.coord (multFstArg i a) * S.coord (multSndArg i a h) := by
rfl
lemma mult_mapIso (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y)
(eX : X ≃ X') (eY : Y ≃ Y') (x : X) (y : Y) (x' : X') (y' : Y') (hx : eX x = x')
(hy : eY y = y') (h : T.color x = τ (S.color y)) :
mult (mapIso d eX T) (mapIso d eY S) x' y' (by subst hx hy; simpa using h) =
mapIso d (Equiv.sumCongr (equivSingleCompl eX hx) (equivSingleCompl eY hy))
(mult T S x y h) := by
rw [mult, mult, mulMarked_mapIso]
congr 1 <;> rw [markSingle_mapIso]
lemma mult_lorentzAction (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y)
(x : X) (y : Y) (h : T.color x = τ (S.color y)) (Λ : LorentzGroup d) :
mult (Λ • T) (Λ • S) x y h = Λ • mult T S x y h := by
rw [mult, mult, ← mulMarked_lorentzAction]
congr 1
all_goals
rw [markSingle, markEmbedding, Equiv.trans_apply]
erw [lorentzAction_mapIso, lorentzAction_mapIso]
rfl
lemma mult_symm (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y)
(x : X) (y : Y) (h : T.color x = τ (S.color y)) :
mapIso d (Equiv.sumComm _ _) (mult T S x y h) = mult S T y x (color_eq_dual_symm h) := by
rw [mult, mult, mulMarked_symm]
/-- An equivalence of types associated with multiplying two consecutive indices,
with the second index appearing on the left. -/
def multSplitLeft {y y' : Y} (hy : y ≠ y') (z : Z) :
{yz // yz ≠ (Sum.inl ⟨y, hy⟩ : {y'' // y'' ≠ y'} ⊕ {z' // z' ≠ z})} ≃
{y'' // y'' ≠ y' ∧ y'' ≠ y} ⊕ {z' // z' ≠ z} :=
Equiv.subtypeSum.trans <|
Equiv.sumCongr (
(Equiv.subtypeEquivRight (fun a => by
obtain ⟨a, p⟩ := a; simp only [ne_eq, Sum.inl.injEq, Subtype.mk.injEq])).trans
(Equiv.subtypeSubtypeEquivSubtypeInter _ _)) <|
Equiv.subtypeUnivEquiv (fun a => Sum.inr_ne_inl)
/-- An equivalence of types associated with multiplying two consecutive indices with the
second index appearing on the right. -/
def multSplitRight {y y' : Y} (hy : y ≠ y') (z : Z) :
{yz // yz ≠ (Sum.inr ⟨y', hy.symm⟩ : {z' // z' ≠ z} ⊕ {y'' // y'' ≠ y})} ≃
{z' // z' ≠ z} ⊕ {y'' // y'' ≠ y' ∧ y'' ≠ y} :=
Equiv.subtypeSum.trans <|
Equiv.sumCongr (Equiv.subtypeUnivEquiv (fun a => Sum.inl_ne_inr)) <|
(Equiv.subtypeEquivRight (fun a => by
obtain ⟨a, p⟩ := a; simp only [ne_eq, Sum.inr.injEq, Subtype.mk.injEq])).trans <|
((Equiv.subtypeSubtypeEquivSubtypeInter _ _).trans
(Equiv.subtypeEquivRight (fun y'' => And.comm)))
/-- An equivalence of types associated with the associativity property of multiplication. -/
def multAssocIso (x : X) {y y' : Y} (hy : y ≠ y') (z : Z) :
{x' // x' ≠ x} ⊕ {yz // yz ≠ (Sum.inl ⟨y, hy⟩ : {y'' // y'' ≠ y'} ⊕ {z' // z' ≠ z})}
≃ {xy // xy ≠ (Sum.inr ⟨y', hy.symm⟩ : {x' // x' ≠ x} ⊕ {y'' // y'' ≠ y})} ⊕ {z' // z' ≠ z} :=
(Equiv.sumCongr (Equiv.refl _) (multSplitLeft hy z)).trans <|
(Equiv.sumAssoc _ _ _).symm.trans <|
(Equiv.sumCongr (multSplitRight hy x).symm (Equiv.refl _))
lemma mult_assoc_color {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y}
{U : RealLorentzTensor d Z} {x : X} {y y' : Y} (hy : y ≠ y') {z : Z}
(h : T.color x = τ (S.color y))
(h' : S.color y' = τ (U.color z)) : (mult (mult T S x y h) U (Sum.inr ⟨y', hy.symm⟩) z h').color
= (mapIso d (multAssocIso x hy z) (mult T (mult S U y' z h') x (Sum.inl ⟨y, hy⟩) h)).color := by
funext a
match a with
| .inl ⟨.inl _, _⟩ => rfl
| .inl ⟨.inr _, _⟩ => rfl
| .inr _ => rfl
/-- An equivalence of index values associated with the associativity property of multiplication. -/
def multAssocIndexValue {T : RealLorentzTensor d X} {S : RealLorentzTensor d Y}
{U : RealLorentzTensor d Z} {x : X} {y y' : Y} (hy : y ≠ y') {z : Z}
(h : T.color x = τ (S.color y)) (h' : S.color y' = τ (U.color z)) :
IndexValue d ((T.mult S x y h).mult U (Sum.inr ⟨y', hy.symm⟩) z h').color ≃
IndexValue d (T.mult (S.mult U y' z h') x (Sum.inl ⟨y, hy⟩) h).color :=
indexValueIso d (multAssocIso x hy z).symm (mult_assoc_color hy h h')
/-- Multiplication of indices is associative, up to a `mapIso` equivalence. -/
lemma mult_assoc (T : RealLorentzTensor d X) (S : RealLorentzTensor d Y) (U : RealLorentzTensor d Z)
(x : X) (y y' : Y) (hy : y ≠ y') (z : Z) (h : T.color x = τ (S.color y))
(h' : S.color y' = τ (U.color z)) : mult (mult T S x y h) U (Sum.inr ⟨y', hy.symm⟩) z h' =
mapIso d (multAssocIso x hy z) (mult T (mult S U y' z h') x (Sum.inl ⟨y, hy⟩) h) := by
apply ext (mult_assoc_color _ _ _) ?_
funext i
trans ∑ a, (∑ b, T.coord (multFstArg (multFstArg i a) b) *
S.coord (multSndArg (multFstArg i a) b h)) * U.coord (multSndArg i a h')
rfl
trans ∑ a, T.coord (multFstArg (multAssocIndexValue hy h h' i) a) *
(∑ b, S.coord (multFstArg (multSndArg (multAssocIndexValue hy h h' i) a h) b) *
U.coord (multSndArg (multSndArg (multAssocIndexValue hy h h' i) a h) b h'))
swap
rw [mapIso_apply_coord, mapIsoFiber_apply, mapIsoFiber_apply, mult_coord_arg, indexValueIso_symm]
rfl
rw [Finset.sum_congr rfl (fun x _ => Finset.sum_mul _ _ _)]
rw [Finset.sum_congr rfl (fun x _ => Finset.mul_sum _ _ _)]
rw [Finset.sum_comm]
refine Finset.sum_congr rfl (fun a _ => Finset.sum_congr rfl (fun b _ => ?_))
rw [mul_assoc]
refine Mathlib.Tactic.Ring.mul_congr rfl (Mathlib.Tactic.Ring.mul_congr ?_ rfl rfl) rfl
apply congrArg
funext c
by_cases hcy : c = y
· subst hcy
rw [multSndArg_on_mem, multFstArg_on_not_mem, multSndArg_on_mem]
rfl
· by_cases hcy' : c = y'
· subst hcy'
rw [multFstArg_on_mem, multSndArg_on_not_mem, multFstArg_on_mem]
· rw [multFstArg_on_not_mem, multSndArg_on_not_mem, multSndArg_on_not_mem,
multFstArg_on_not_mem]
rw [multAssocIndexValue, indexValueIso_eq_symm, indexValueIso_symm_apply']
simp only [ne_eq, Function.comp_apply, Equiv.symm_symm_apply, mult_color, Sum.elim_inr,
colorsIndexCast, Equiv.cast_refl, Equiv.refl_symm]
erw [Equiv.refl_apply]
rfl
exact hcy'
simpa using hcy
end RealLorentzTensor

36
HepLean/SpaceTime/LorentzTensor/Real/MultiplicationUnit.lean
View file

@ -27,7 +27,7 @@ The main results of this file are:
namespace RealLorentzTensor
variable {d : ℕ} {X Y : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
(T : RealLorentzTensor d X) (c : X → Colors) (Λ Λ' : LorentzGroup d) {μ : Colors}
(T : RealLorentzTensor d X) (c : X → Color) (Λ Λ' : LorentzGroup d) {μ : Color}
open Marked
@ -38,7 +38,7 @@ open Marked
-/
/-- The unit for the multiplication of Lorentz tensors. -/
def mulUnit (d : ℕ) (μ : Colors) : Marked d (Fin 1) 1 :=
def mulUnit (d : ℕ) (μ : Color) : Marked d (Fin 1) 1 :=
match μ with
| .up => mapIso d ((Equiv.emptySum Empty (Fin (1 + 1))).trans finSumFinEquiv.symm)
(ofMatUpDown 1)
@ -54,23 +54,23 @@ lemma mulUnit_down_coord : (mulUnit d Colors.down).coord = fun i =>
rfl
@[simp]
lemma mulUnit_markedColor (μ : Colors) : (mulUnit d μ).markedColor 0 = τ μ := by
lemma mulUnit_markedColor (μ : Color) : (mulUnit d μ).markedColor 0 = τ μ := by
cases μ
case up => rfl
case down => rfl
lemma mulUnit_dual_markedColor (μ : Colors) : τ ((mulUnit d μ).markedColor 0) = μ := by
lemma mulUnit_dual_markedColor (μ : Color) : τ ((mulUnit d μ).markedColor 0) = μ := by
cases μ
case up => rfl
case down => rfl
@[simp]
lemma mulUnit_unmarkedColor (μ : Colors) : (mulUnit d μ).unmarkedColor 0 = μ := by
lemma mulUnit_unmarkedColor (μ : Color) : (mulUnit d μ).unmarkedColor 0 = μ := by
cases μ
case up => rfl
case down => rfl
lemma mulUnit_unmarkedColor_eq_dual_marked (μ : Colors) :
lemma mulUnit_unmarkedColor_eq_dual_marked (μ : Color) :
(mulUnit d μ).unmarkedColor = τ ∘ (mulUnit d μ).markedColor := by
funext x
fin_cases x
@ -78,7 +78,7 @@ lemma mulUnit_unmarkedColor_eq_dual_marked (μ : Colors) :
mulUnit_markedColor]
exact color_eq_dual_symm rfl
lemma mulUnit_coord_diag (μ : Colors) (i : (mulUnit d μ).UnmarkedIndexValue) :
lemma mulUnit_coord_diag (μ : Color) (i : (mulUnit d μ).UnmarkedIndexValue) :
(mulUnit d μ).coord (splitIndexValue.symm (i,
indexValueDualIso d (mulUnit_unmarkedColor_eq_dual_marked μ) i)) = 1 := by
cases μ
@ -92,7 +92,7 @@ lemma mulUnit_coord_diag (μ : Colors) (i : (mulUnit d μ).UnmarkedIndexValue) :
rfl
next h => exact False.elim (h rfl)
lemma mulUnit_coord_off_diag (μ : Colors) (i: (mulUnit d μ).UnmarkedIndexValue)
lemma mulUnit_coord_off_diag (μ : Color) (i: (mulUnit d μ).UnmarkedIndexValue)
(b : (mulUnit d μ).MarkedIndexValue)
(hb : b ≠ indexValueDualIso d (mulUnit_unmarkedColor_eq_dual_marked μ) i) :
(mulUnit d μ).coord (splitIndexValue.symm (i, b)) = 0 := by
@ -118,7 +118,7 @@ lemma mulUnit_coord_off_diag (μ : Colors) (i: (mulUnit d μ).UnmarkedIndexValue
exact h
exact hb (id (Eq.symm h1))
lemma mulUnit_right (μ : Colors) (T : Marked d X 1) (h : T.markedColor 0 = μ) :
lemma mulUnit_right (μ : Color) (T : Marked d X 1) (h : T.markedColor 0 = μ) :
multMarked T (mulUnit d μ) (h.trans (mulUnit_dual_markedColor μ).symm) = T := by
refine ext ?_ ?_
· funext a
@ -130,9 +130,9 @@ lemma mulUnit_right (μ : Colors) (T : Marked d X 1) (h : T.markedColor 0 = μ)
funext i
rw [mulMarked_indexValue_right]
change ∑ j,
T.coord (splitIndexValue.symm ((indexValueSumEquiv i).1, _)) *
(mulUnit d μ).coord (splitIndexValue.symm ((indexValueSumEquiv i).2, j)) = _
let y := indexValueDualIso d (mulUnit_unmarkedColor_eq_dual_marked μ) (indexValueSumEquiv i).2
T.coord (splitIndexValue.symm ((indexValueTensorator i).1, _)) *
(mulUnit d μ).coord (splitIndexValue.symm ((indexValueTensorator i).2, j)) = _
let y := indexValueDualIso d (mulUnit_unmarkedColor_eq_dual_marked μ) (indexValueTensorator i).2
erw [Finset.sum_eq_single_of_mem y]
rw [mulUnit_coord_diag]
simp only [Fin.isValue, mul_one]
@ -140,14 +140,14 @@ lemma mulUnit_right (μ : Colors) (T : Marked d X 1) (h : T.markedColor 0 = μ)
funext a
match a with
| .inl a =>
change (indexValueSumEquiv i).1 a = _
change (indexValueTensorator i).1 a = _
rfl
| .inr 0 =>
change oneMarkedIndexValue
((colorsIndexDualCast (Eq.trans h (Eq.symm (mulUnit_dual_markedColor μ)))).symm
((colorIndexDualCast (Eq.trans h (Eq.symm (mulUnit_dual_markedColor μ)))).symm
(oneMarkedIndexValue.symm y)) 0 = _
rw [indexValueIso_eq_symm, indexValueIso_symm_apply']
simp only [Fin.isValue, oneMarkedIndexValue, colorsIndexDualCast, colorsIndexCast,
simp only [Fin.isValue, oneMarkedIndexValue, colorIndexDualCast, colorIndexCast,
Equiv.coe_fn_symm_mk, indexValueDualIso_apply, Equiv.trans_apply, Equiv.cast_apply,
Equiv.symm_trans_apply, Equiv.cast_symm, Equiv.symm_symm, Equiv.apply_symm_apply, cast_cast,
Equiv.coe_fn_mk, Equiv.refl_symm, Equiv.coe_refl, Function.comp_apply, id_eq, mul_color,
@ -157,15 +157,15 @@ lemma mulUnit_right (μ : Colors) (T : Marked d X 1) (h : T.markedColor 0 = μ)
intro b _ hab
rw [mul_eq_zero]
apply Or.inr
exact mulUnit_coord_off_diag μ (indexValueSumEquiv i).2 b hab
exact mulUnit_coord_off_diag μ (indexValueTensorator i).2 b hab
lemma mulUnit_left (μ : Colors) (T : Marked d X 1) (h : T.markedColor 0 = μ) :
lemma mulUnit_left (μ : Color) (T : Marked d X 1) (h : T.markedColor 0 = μ) :
multMarked (mulUnit d μ) T ((mulUnit_markedColor μ).trans (congrArg τ h.symm)) =
mapIso d (Equiv.sumComm X (Fin 1)) T := by
rw [← mult_symmd_symm, mulUnit_right]
exact h
lemma mulUnit_lorentzAction (μ : Colors) (Λ : LorentzGroup d) :
lemma mulUnit_lorentzAction (μ : Color) (Λ : LorentzGroup d) :
Λ • mulUnit d μ = mulUnit d μ := by
match μ with
| Colors.up =>

177
HepLean/SpaceTime/LorentzTensor/Real/TensorProducts.lean
View file

@ -19,7 +19,7 @@ open Set LinearMap Submodule
variable {d : ℕ} {X Y Y' X' : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
[Fintype Y'] [DecidableEq Y'] [Fintype X'] [DecidableEq X']
(cX : X → Colors) (cY : Y → Colors)
(cX : X → Color) (cY : Y → Color)
/-!
@ -31,65 +31,60 @@ variable {d : ℕ} {X Y Y' X' : Type} [Fintype X] [DecidableEq X] [Fintype Y] [
/-- An equivalence between `ColorFiber d (Sum.elim cX cY)` and
`ColorFiber d cX ⊗[ℝ] ColorFiber d cY`. This is related to the `tensorator` of
the monoidal functor defined by `ColorFiber`, hence the terminology. -/
def tensorator {cX : X → Colors} {cY : Y → Colors} :
ColorFiber d (Sum.elim cX cY) ≃ₗ[ℝ] ColorFiber d cX ⊗[ℝ] ColorFiber d cY :=
(basisColorFiber (Sum.elim cX cY)).equiv (basisProd cX cY) indexValueSumEquiv
def tensorator {cX : X → Color} {cY : Y → Color} :
RealLorentzTensor d (Sum.elim cX cY) ≃ₗ[ℝ] RealLorentzTensor d cX ⊗[ℝ] RealLorentzTensor d cY :=
(basis (Sum.elim cX cY)).equiv (basisProd cX cY) indexValueTensorator
lemma tensorator_symm_apply {cX : X → Colors} {cY : Y → Colors}
(X : ColorFiber d cX ⊗[ℝ] ColorFiber d cY) (i : IndexValue d (Sum.elim cX cY)) :
(tensorator.symm X) i = (basisProd cX cY).repr X (indexValueSumEquiv i) := by
lemma tensorator_symm_apply {cX : X → Color} {cY : Y → Color}
(X : RealLorentzTensor d cX ⊗[ℝ] RealLorentzTensor d cY) (i : IndexValue d (Sum.elim cX cY)) :
(tensorator.symm X) i = (basisProd cX cY).repr X (indexValueTensorator i) := by
rfl
/-! TODO : Move -/
lemma tensorator_mapIso_cond {cX : X → Colors} {cY : Y → Colors} {cX' : X' → Colors}
{cY' : Y' → Colors} {eX : X ≃ X'} {eY : Y ≃ Y'} (hX : cX = cX' ∘ eX) (hY : cY = cY' ∘ eY) :
Sum.elim cX cY = Sum.elim cX' cY' ∘ ⇑(eX.sumCongr eY) := by
subst hX hY
ext1 x
simp_all only [Function.comp_apply, Equiv.sumCongr_apply]
cases x with
| inl val => simp_all only [Sum.elim_inl, Function.comp_apply, Sum.map_inl]
| inr val_1 => simp_all only [Sum.elim_inr, Function.comp_apply, Sum.map_inr]
/-- The naturality condition for the `tensorator`. -/
lemma tensorator_mapIso {cX : X → Colors} {cY : Y → Colors} {cX' : X' → Colors}
{cY' : Y' → Colors} (eX : X ≃ X') (eY : Y ≃ Y') (hX : cX = cX' ∘ eX) (hY : cY = cY' ∘ eY) :
(mapIsoFiber d (Equiv.sumCongr eX eY) (tensorator_mapIso_cond hX hY)).trans tensorator =
tensorator.trans (TensorProduct.congr (mapIsoFiber d eX hX) (mapIsoFiber d eY hY)) := by
apply (basisColorFiber (Sum.elim cX cY)).ext'
lemma tensorator_mapIso {cX : X → Color} {cY : Y → Color} {cX' : X' → Color}
{cY' : Y' → Color} (eX : X ≃ X') (eY : Y ≃ Y') (hX : cX = cX' ∘ eX) (hY : cY = cY' ∘ eY) :
(@mapIso _ _ d (Equiv.sumCongr eX eY) _ _ (tensorator_mapIso_cond hX hY)).trans tensorator =
tensorator.trans (TensorProduct.congr (mapIso eX hX) (mapIso eY hY)) := by
apply (basis (Sum.elim cX cY)).ext'
intro i
simp
nth_rewrite 2 [tensorator]
simp
rw [Basis.tensorProduct_apply, TensorProduct.congr_tmul, mapIsoFiber_basis]
rw [tensorator]
simp
simp only [basisProd, Basis.equiv_apply]
rw [Basis.tensorProduct_apply, mapIsoFiber_basis, mapIsoFiber_basis]
congr
sorry
sorry
rw [← Equiv.trans_apply, indexValueTensorator_indexValueMapIso]
rfl
exact hY
rw [← Equiv.trans_apply, indexValueTensorator_indexValueMapIso]
rfl
exact hX
lemma tensorator_lorentzAction (Λ : LorentzGroup d) :
(tensorator).toLinearMap ∘ₗ lorentzActionFiber Λ
= (TensorProduct.map (lorentzActionFiber Λ) (lorentzActionFiber Λ) ) ∘ₗ
(tensorator).toLinearMap ∘ₗ lorentzAction Λ
= (TensorProduct.map (lorentzAction Λ) (lorentzAction Λ) ) ∘ₗ
((@tensorator d X Y _ _ _ _ cX cY).toLinearMap) := by
apply (basisColorFiber (Sum.elim cX cY)).ext
apply (basis (Sum.elim cX cY)).ext
intro i
nth_rewrite 2 [tensorator]
simp only [coe_comp, LinearEquiv.coe_coe, Function.comp_apply, Basis.equiv_apply]
rw [basisProd, Basis.tensorProduct_apply, TensorProduct.map_tmul, lorentzActionFiber_basis,
lorentzActionFiber_basis, lorentzActionFiber_basis, map_sum, tmul_sum]
rw [basisProd, Basis.tensorProduct_apply, TensorProduct.map_tmul, lorentzAction_basis,
lorentzAction_basis, lorentzAction_basis, map_sum, tmul_sum]
simp only [sum_tmul]
rw [← Equiv.sum_comp (indexValueSumEquiv).symm, Fintype.sum_prod_type, Finset.sum_comm]
rw [← Equiv.sum_comp (indexValueTensorator).symm, Fintype.sum_prod_type, Finset.sum_comm]
refine Finset.sum_congr rfl (fun j _ => (Finset.sum_congr rfl (fun k _ => ?_)))
rw [tmul_smul, smul_tmul, tmul_smul, smul_smul, map_smul]
congr 1
· rw [toTensorRepMat_of_indexValueSumEquiv, Equiv.apply_symm_apply, mul_comm]
· simp [tensorator]
lemma tensorator_lorentzAction_apply (Λ : LorentzGroup d) (T : ColorFiber d (Sum.elim cX cY)) :
tensorator (lorentzActionFiber Λ T) =
TensorProduct.map (lorentzActionFiber Λ) (lorentzActionFiber Λ) (tensorator T) := by
lemma tensorator_lorentzAction_apply (Λ : LorentzGroup d) (T : RealLorentzTensor d (Sum.elim cX cY)) :
tensorator (Λ • T) =
TensorProduct.map (lorentzAction Λ) (lorentzAction Λ) (tensorator T) := by
erw [← LinearMap.comp_apply, tensorator_lorentzAction]
rfl
@ -106,33 +101,33 @@ def decompEmbedSet (f : Y ↪ X) :
Equiv.sumCongr ((Equiv.subtypeEquivRight (by simp))) <|
(Function.Embedding.toEquivRange f).symm
def decompEmbedColorLeft (f : Y ↪ X) : {x // x ∈ (Finset.image f Finset.univ)ᶜ} → Colors :=
def decompEmbedColorLeft (f : Y ↪ X) : {x // x ∈ (Finset.image f Finset.univ)ᶜ} → Color :=
(cX ∘ (decompEmbedSet f).symm) ∘ Sum.inl
def decompEmbedColorRight (f : Y ↪ X) : Y → Colors :=
def decompEmbedColorRight (f : Y ↪ X) : Y → Color :=
(cX ∘ (decompEmbedSet f).symm) ∘ Sum.inr
/-- Decomposes a tensor into a tensor product based on an embedding. -/
def decompEmbed (f : Y ↪ X) :
ColorFiber d cX ≃ₗ[ℝ] ColorFiber d (decompEmbedColorLeft cX f) ⊗[ℝ] ColorFiber d (cX ∘ f) :=
(@mapIsoFiber _ _ d (decompEmbedSet f) cX (Sum.elim (decompEmbedColorLeft cX f)
RealLorentzTensor d cX ≃ₗ[ℝ] RealLorentzTensor d (decompEmbedColorLeft cX f) ⊗[ℝ] RealLorentzTensor d (cX ∘ f) :=
(@mapIso _ _ d (decompEmbedSet f) cX (Sum.elim (decompEmbedColorLeft cX f)
(decompEmbedColorRight cX f)) (by
simpa [decompEmbedColorLeft, decompEmbedColorRight] using (Equiv.comp_symm_eq _ _ _).mp rfl)).trans
tensorator
lemma decompEmbed_lorentzAction_apply {f : Y ↪ X} (Λ : LorentzGroup d) (T : ColorFiber d cX) :
decompEmbed cX f (lorentzActionFiber Λ T) =
TensorProduct.map (lorentzActionFiber Λ) (lorentzActionFiber Λ) (decompEmbed cX f T) := by
lemma decompEmbed_lorentzAction_apply {f : Y ↪ X} (Λ : LorentzGroup d) (T : RealLorentzTensor d cX) :
decompEmbed cX f (Λ • T) =
TensorProduct.map (lorentzAction Λ) (lorentzAction Λ) (decompEmbed cX f T) := by
rw [decompEmbed]
simp
rw [lorentzActionFiber_mapIsoFiber]
rw [lorentzAction_mapIso]
exact tensorator_lorentzAction_apply (decompEmbedColorLeft cX f) (decompEmbedColorRight cX f) Λ
((mapIsoFiber d (decompEmbedSet f) (decompEmbed.proof_2 cX f)) T)
((mapIso (decompEmbedSet f) (decompEmbed.proof_2 cX f)) T)
def decompEmbedProd (f : X' ↪ X) (g : Y' ↪ Y) :
ColorFiber d cX ⊗[ℝ] ColorFiber d cY ≃ₗ[ℝ]
ColorFiber d (Sum.elim (decompEmbedColorLeft cX f) (decompEmbedColorLeft cY g))
⊗[ℝ] (ColorFiber d (cX ∘ f) ⊗[ℝ] ColorFiber d (cY ∘ g)) :=
RealLorentzTensor d cX ⊗[ℝ] RealLorentzTensor d cY ≃ₗ[ℝ]
RealLorentzTensor d (Sum.elim (decompEmbedColorLeft cX f) (decompEmbedColorLeft cY g))
⊗[ℝ] (RealLorentzTensor d (cX ∘ f) ⊗[ℝ] RealLorentzTensor d (cY ∘ g)) :=
(TensorProduct.congr (decompEmbed cX f) (decompEmbed cY g)).trans <|
(TensorProduct.assoc ℝ _ _ _).trans <|
(TensorProduct.congr (LinearEquiv.refl ℝ _)
@ -144,95 +139,5 @@ def decompEmbedProd (f : X' ↪ X) (g : Y' ↪ Y) :
/-- The contraction of all indices of two tensors with dual index-colors.
This is a bilinear map to ℝ. -/
@[simps!]
def contrAll {f1 : X → Colors} {f2 : Y → Colors} (e : X ≃ Y) (hc : f1 = τ ∘ f2 ∘ e) :
ColorFiber d f1 →ₗ[ℝ] ColorFiber d f2 →ₗ[ℝ] ℝ where
toFun T := {
toFun := fun S => ∑ i, T i * S (indexValueDualIso d e hc i),
map_add' := fun S F => by
trans ∑ i, (T i * S (indexValueDualIso d e hc i) + T i * F (indexValueDualIso d e hc i))
exact Finset.sum_congr rfl (fun i _ => mul_add _ _ _ )
exact Finset.sum_add_distrib,
map_smul' := fun r S => by
trans ∑ i , r * (T i * S (indexValueDualIso d e hc i))
refine Finset.sum_congr rfl (fun x _ => ?_)
ring_nf
rw [mul_assoc]
rfl
rw [← Finset.mul_sum]
rfl}
map_add' := fun T S => by
ext F
trans ∑ i , (T i * F (indexValueDualIso d e hc i) + S i * F (indexValueDualIso d e hc i))
exact Finset.sum_congr rfl (fun x _ => add_mul _ _ _)
exact Finset.sum_add_distrib
map_smul' := fun r T => by
ext S
trans ∑ i , r * (T i * S (indexValueDualIso d e hc i))
refine Finset.sum_congr rfl (fun x _ => mul_assoc _ _ _)
rw [← Finset.mul_sum]
rfl
lemma contrAll_symm {f1 : X → Colors} {f2 : Y → Colors} (e : X ≃ Y)
(h : f1 = τ ∘ f2 ∘ e) (T : ColorFiber d f1) (S : ColorFiber d f2) :
contrAll e h T S = contrAll e.symm (indexValueDualIso_cond_symm h) S T := by
rw [contrAll_apply_apply, contrAll_apply_apply, ← Equiv.sum_comp (indexValueDualIso d e h)]
refine Finset.sum_congr rfl (fun i _ => ?_)
rw [mul_comm, ← Equiv.trans_apply]
simp
lemma contrAll_mapIsoFiber_right {f1 : X → Colors} {f2 : Y → Colors}
{g2 : Y' → Colors} (e : X ≃ Y) (eY : Y ≃ Y')
(h : f1 = τ ∘ f2 ∘ e) (hY : f2 = g2 ∘ eY) (T : ColorFiber d f1) (S : ColorFiber d f2) :
contrAll e h T S = contrAll (e.trans eY) (indexValueDualIso_cond_trans_indexValueIso h hY)
T (mapIsoFiber d eY hY S) := by
rw [contrAll_apply_apply, contrAll_apply_apply]
refine Finset.sum_congr rfl (fun i _ => Mathlib.Tactic.Ring.mul_congr rfl ?_ rfl)
rw [mapIsoFiber_apply, ← Equiv.trans_apply]
simp only [indexValueDualIso_trans_indexValueIso]
congr
ext1 x
simp only [Equiv.trans_apply, Equiv.symm_apply_apply]
lemma contrAll_mapIsoFiber_left {f1 : X → Colors} {f2 : Y → Colors}
{g1 : X' → Colors} (e : X ≃ Y) (eX : X ≃ X')
(h : f1 = τ ∘ f2 ∘ e) (hX : f1 = g1 ∘ eX) (T : ColorFiber d f1) (S : ColorFiber d f2) :
contrAll e h T S = contrAll (eX.symm.trans e)
(indexValueIso_trans_indexValueDualIso_cond ((Equiv.eq_comp_symm eX g1 f1).mpr hX.symm) h)
(mapIsoFiber d eX hX T) S := by
rw [contrAll_symm, contrAll_mapIsoFiber_right _ eX _ hX, contrAll_symm]
rfl
lemma contrAll_lorentzAction {f1 : X → Colors} {f2 : Y → Colors} (e : X ≃ Y)
(hc : f1 = τ ∘ f2 ∘ e) (T : ColorFiber d f1) (S : ColorFiber d f2) (Λ : LorentzGroup d) :
contrAll e hc (lorentzActionFiber Λ T) (lorentzActionFiber Λ S) = contrAll e hc T S := by
change ∑ i, (∑ j, toTensorRepMat Λ i j * T j) *
(∑ k, toTensorRepMat Λ (indexValueDualIso d e hc i) k * S k) = _
trans ∑ i, ∑ j, ∑ k, (toTensorRepMat Λ (indexValueDualIso d e hc i) k * toTensorRepMat Λ i j)
* T j * S k
· apply Finset.sum_congr rfl (fun x _ => ?_)
rw [Finset.sum_mul_sum]
apply Finset.sum_congr rfl (fun j _ => ?_)
apply Finset.sum_congr rfl (fun k _ => ?_)
ring
rw [Finset.sum_comm]
trans ∑ j, ∑ k, ∑ i, (toTensorRepMat Λ (indexValueDualIso d e hc i) k
* toTensorRepMat Λ i j) * T j * S k
· apply Finset.sum_congr rfl (fun j _ => ?_)
rw [Finset.sum_comm]
trans ∑ j, ∑ k, (toTensorRepMat 1 (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) k) j) * T j * S k
· apply Finset.sum_congr rfl (fun j _ => Finset.sum_congr rfl (fun k _ => ?_))
rw [← Finset.sum_mul, ← Finset.sum_mul]
erw [toTensorRepMat_indexValueDualIso_sum]
rw [Finset.sum_comm]
trans ∑ k, T (indexValueDualIso d e.symm (indexValueDualIso_cond_symm hc) k) * S k
· apply Finset.sum_congr rfl (fun k _ => ?_)
rw [← Finset.sum_mul, ← toTensorRepMat_one_coord_sum' T]
rw [← Equiv.sum_comp (indexValueDualIso d e hc), ← indexValueDualIso_symm e hc]
simp only [Equiv.symm_apply_apply, contrAll_apply_apply]
end RealLorentzTensor
end