feat: Start adding expansions in terms of basis

This commit is contained in:
jstoobysmith 2024-10-23 05:56:00 +00:00
parent 5a0e52e726
commit 1148234929
5 changed files with 196 additions and 2 deletions

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@ -24,6 +24,23 @@ namespace Lorentz
def contrMetricVal : (complexContr ⊗ complexContr).V :=
contrContrToMatrix.symm ((@minkowskiMatrix 3).map ofReal)
/-- The expansion of `contrMetricVal` into basis vectors. -/
lemma contrMetricVal_expand_tmul : contrMetricVal =
complexContrBasis (Sum.inl 0) ⊗ₜ[] complexContrBasis (Sum.inl 0)
- complexContrBasis (Sum.inr 0) ⊗ₜ[] complexContrBasis (Sum.inr 0)
- complexContrBasis (Sum.inr 1) ⊗ₜ[] complexContrBasis (Sum.inr 1)
- complexContrBasis (Sum.inr 2) ⊗ₜ[] complexContrBasis (Sum.inr 2) := by
simp only [Action.instMonoidalCategory_tensorObj_V, contrMetricVal, Fin.isValue]
erw [contrContrToMatrix_symm_expand_tmul]
simp only [map_apply, ofReal_eq_coe, coe_smul, Fintype.sum_sum_type, Finset.univ_unique,
Fin.default_eq_zero, Fin.isValue, Finset.sum_singleton, Fin.sum_univ_three, ne_eq, reduceCtorEq,
not_false_eq_true, minkowskiMatrix.off_diag_zero, zero_smul, add_zero, zero_add, Sum.inr.injEq,
zero_ne_one, Fin.reduceEq, one_ne_zero]
rw [minkowskiMatrix.inl_0_inl_0, minkowskiMatrix.inr_i_inr_i,
minkowskiMatrix.inr_i_inr_i, minkowskiMatrix.inr_i_inr_i]
simp only [Fin.isValue, one_smul, neg_smul]
rfl
/-- The metric `ηᵃᵃ` as a morphism `𝟙_ (Rep SL(2,)) ⟶ complexContr ⊗ complexContr`,
making its invariance under the action of `SL(2,)`. -/
def contrMetric : 𝟙_ (Rep SL(2,)) ⟶ complexContr ⊗ complexContr where
@ -51,10 +68,16 @@ def contrMetric : 𝟙_ (Rep SL(2,)) ⟶ complexContr ⊗ complexContr wh
apply congrArg
simp only [LorentzGroup.toComplex_mul_minkowskiMatrix_mul_transpose]
lemma contrMetric_apply_one : contrMetric.hom (1 : ) = contrMetricVal := by
change contrMetric.hom.toFun (1 : ) = contrMetricVal
simp only [Action.instMonoidalCategory_tensorObj_V, Action.instMonoidalCategory_tensorUnit_V,
contrMetric, AddHom.toFun_eq_coe, AddHom.coe_mk, one_smul]
/-- The metric `ηᵢᵢ` as an element of `(complexCo ⊗ complexCo).V`. -/
def coMetricVal : (complexCo ⊗ complexCo).V :=
coCoToMatrix.symm ((@minkowskiMatrix 3).map ofReal)
/-- The expansion of `coMetricVal` into basis vectors. -/
lemma coMetricVal_expand_tmul : coMetricVal =
complexCoBasis (Sum.inl 0) ⊗ₜ[] complexCoBasis (Sum.inl 0)
- complexCoBasis (Sum.inr 0) ⊗ₜ[] complexCoBasis (Sum.inr 0)
@ -102,7 +125,8 @@ def coMetric : 𝟙_ (Rep SL(2,)) ⟶ complexCo ⊗ complexCo where
lemma coMetric_apply_one : coMetric.hom (1 : ) = coMetricVal := by
change coMetric.hom.toFun (1 : ) = coMetricVal
simp [coMetric]
simp only [Action.instMonoidalCategory_tensorObj_V, Action.instMonoidalCategory_tensorUnit_V,
coMetric, AddHom.toFun_eq_coe, AddHom.coe_mk, one_smul]
end Lorentz
end

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@ -27,6 +27,19 @@ def contrContrToMatrix : (complexContr ⊗ complexContr).V ≃ₗ[]
Finsupp.linearEquivFunOnFinite ((Fin 1 ⊕ Fin 3) × (Fin 1 ⊕ Fin 3)) ≪≫ₗ
LinearEquiv.curry (Fin 1 ⊕ Fin 3) (Fin 1 ⊕ Fin 3)
/-- Expanding `contrContrToMatrix` in terms of the standard basis. -/
lemma contrContrToMatrix_symm_expand_tmul (M : Matrix (Fin 1 ⊕ Fin 3) (Fin 1 ⊕ Fin 3) ) :
contrContrToMatrix.symm M =
∑ i, ∑ j, M i j • (complexContrBasis i ⊗ₜ[] complexContrBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, contrContrToMatrix, LinearEquiv.trans_symm,
LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply complexContrBasis complexContrBasis i j]
rfl
· simp
/-- Equivalence of `complexCo ⊗ complexCo` to `4 x 4` complex matrices. -/
def coCoToMatrix : (complexCo ⊗ complexCo).V ≃ₗ[]
Matrix (Fin 1 ⊕ Fin 3) (Fin 1 ⊕ Fin 3) :=

View file

@ -33,60 +33,180 @@ def leftLeftToMatrix : (leftHanded ⊗ leftHanded).V ≃ₗ[] Matrix (Fin 2)
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `leftLeftToMatrix` in terms of the standard basis. -/
lemma leftLeftToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
leftLeftToMatrix.symm M = ∑ i, ∑ j, M i j • (leftBasis i ⊗ₜ[] leftBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, leftLeftToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply leftBasis leftBasis i j]
rfl
· simp
/-- Equivalence of `altLeftHanded ⊗ altLeftHanded` to `2 x 2` complex matrices. -/
def altLeftaltLeftToMatrix : (altLeftHanded ⊗ altLeftHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct altLeftBasis altLeftBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `altLeftaltLeftToMatrix` in terms of the standard basis. -/
lemma altLeftaltLeftToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
altLeftaltLeftToMatrix.symm M = ∑ i, ∑ j, M i j • (altLeftBasis i ⊗ₜ[] altLeftBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, altLeftaltLeftToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply altLeftBasis altLeftBasis i j]
rfl
· simp
/-- Equivalence of `leftHanded ⊗ altLeftHanded` to `2 x 2` complex matrices. -/
def leftAltLeftToMatrix : (leftHanded ⊗ altLeftHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct leftBasis altLeftBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `leftAltLeftToMatrix` in terms of the standard basis. -/
lemma leftAltLeftToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
leftAltLeftToMatrix.symm M = ∑ i, ∑ j, M i j • (leftBasis i ⊗ₜ[] altLeftBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, leftAltLeftToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply leftBasis altLeftBasis i j]
rfl
· simp
/-- Equivalence of `altLeftHanded ⊗ leftHanded` to `2 x 2` complex matrices. -/
def altLeftLeftToMatrix : (altLeftHanded ⊗ leftHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct altLeftBasis leftBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `altLeftLeftToMatrix` in terms of the standard basis. -/
lemma altLeftLeftToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
altLeftLeftToMatrix.symm M = ∑ i, ∑ j, M i j • (altLeftBasis i ⊗ₜ[] leftBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, altLeftLeftToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply altLeftBasis leftBasis i j]
rfl
· simp
/-- Equivalence of `rightHanded ⊗ rightHanded` to `2 x 2` complex matrices. -/
def rightRightToMatrix : (rightHanded ⊗ rightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct rightBasis rightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `rightRightToMatrix` in terms of the standard basis. -/
lemma rightRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
rightRightToMatrix.symm M = ∑ i, ∑ j, M i j • (rightBasis i ⊗ₜ[] rightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, rightRightToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply rightBasis rightBasis i j]
rfl
· simp
/-- Equivalence of `altRightHanded ⊗ altRightHanded` to `2 x 2` complex matrices. -/
def altRightAltRightToMatrix : (altRightHanded ⊗ altRightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct altRightBasis altRightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `altRightAltRightToMatrix` in terms of the standard basis. -/
lemma altRightAltRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
altRightAltRightToMatrix.symm M = ∑ i, ∑ j, M i j • (altRightBasis i ⊗ₜ[] altRightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, altRightAltRightToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply altRightBasis altRightBasis i j]
rfl
· simp
/-- Equivalence of `rightHanded ⊗ altRightHanded` to `2 x 2` complex matrices. -/
def rightAltRightToMatrix : (rightHanded ⊗ altRightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct rightBasis altRightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `rightAltRightToMatrix` in terms of the standard basis. -/
lemma rightAltRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
rightAltRightToMatrix.symm M = ∑ i, ∑ j, M i j • (rightBasis i ⊗ₜ[] altRightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, rightAltRightToMatrix, LinearEquiv.trans_symm,
LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply rightBasis altRightBasis i j]
rfl
· simp
/-- Equivalence of `altRightHanded ⊗ rightHanded` to `2 x 2` complex matrices. -/
def altRightRightToMatrix : (altRightHanded ⊗ rightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct altRightBasis rightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `altRightRightToMatrix` in terms of the standard basis. -/
lemma altRightRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
altRightRightToMatrix.symm M = ∑ i, ∑ j, M i j • (altRightBasis i ⊗ₜ[] rightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, altRightRightToMatrix, LinearEquiv.trans_symm,
LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply altRightBasis rightBasis i j]
rfl
· simp
/-- Equivalence of `altLeftHanded ⊗ altRightHanded` to `2 x 2` complex matrices. -/
def altLeftAltRightToMatrix : (altLeftHanded ⊗ altRightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct altLeftBasis altRightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `altLeftAltRightToMatrix` in terms of the standard basis. -/
lemma altLeftAltRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
altLeftAltRightToMatrix.symm M = ∑ i, ∑ j, M i j • (altLeftBasis i ⊗ₜ[] altRightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, altLeftAltRightToMatrix,
LinearEquiv.trans_symm, LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply altLeftBasis altRightBasis i j]
rfl
· simp
/-- Equivalence of `leftHanded ⊗ rightHanded` to `2 x 2` complex matrices. -/
def leftRightToMatrix : (leftHanded ⊗ rightHanded).V ≃ₗ[] Matrix (Fin 2) (Fin 2) :=
(Basis.tensorProduct leftBasis rightBasis).repr ≪≫ₗ
Finsupp.linearEquivFunOnFinite (Fin 2 × Fin 2) ≪≫ₗ
LinearEquiv.curry (Fin 2) (Fin 2)
/-- Expanding `leftRightToMatrix` in terms of the standard basis. -/
lemma leftRightToMatrix_symm_expand_tmul (M : Matrix (Fin 2) (Fin 2) ) :
leftRightToMatrix.symm M = ∑ i, ∑ j, M i j • (leftBasis i ⊗ₜ[] rightBasis j) := by
simp only [Action.instMonoidalCategory_tensorObj_V, leftRightToMatrix, LinearEquiv.trans_symm,
LinearEquiv.trans_apply, Basis.repr_symm_apply]
rw [Finsupp.linearCombination_apply_of_mem_supported (s := Finset.univ)]
· erw [Finset.sum_product]
refine Finset.sum_congr rfl (fun i _ => Finset.sum_congr rfl (fun j _ => ?_))
erw [Basis.tensorProduct_apply leftBasis rightBasis i j]
rfl
· simp
/-!
## Group actions