PhysLean/HepLean/Tensors/ComplexLorentz/Metrics/Lemmas.lean
2024-10-29 13:46:18 +00:00

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/-
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.Tensors.ComplexLorentz.Metrics.Basis
import HepLean.Tensors.ComplexLorentz.Basis
/-!
## Metrics and basis expansions
-/
open IndexNotation
open CategoryTheory
open MonoidalCategory
open Matrix
open MatrixGroups
open Complex
open TensorProduct
open IndexNotation
open CategoryTheory
open TensorTree
open OverColor.Discrete
noncomputable section
namespace complexLorentzTensor
/-- The map to color one gets when multiplying left and right metrics. -/
def leftMetricMulRightMap := (Sum.elim ![Color.upL, Color.upL] ![Color.upR, Color.upR]) ∘
finSumFinEquiv.symm
lemma leftMetric_mul_rightMetric : {εL | α α' ⊗ εR | β β'}ᵀ.tensor
= basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 0 | 3 => 1)
- basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 1 | 3 => 0)
- basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 0 | 3 => 1)
+ basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 1 | 3 => 0) := by
rw [prod_tensor_eq_fst (leftMetric_expand_tree)]
rw [prod_tensor_eq_snd (rightMetric_expand_tree)]
rw [prod_add_both]
rw [add_tensor_eq_fst <| add_tensor_eq_fst <| smul_prod _ _ _]
rw [add_tensor_eq_fst <| add_tensor_eq_fst <| smul_tensor_eq <| prod_smul _ _ _]
rw [add_tensor_eq_fst <| add_tensor_eq_fst <| smul_smul _ _ _]
rw [add_tensor_eq_fst <| add_tensor_eq_fst <| smul_eq_one _ _ (by simp)]
rw [add_tensor_eq_fst <| add_tensor_eq_snd <| smul_prod _ _ _]
rw [add_tensor_eq_snd <| add_tensor_eq_fst <| prod_smul _ _ _]
rw [add_tensor_eq_fst <| add_tensor_eq_fst <| prod_basisVector_tree _ _]
rw [add_tensor_eq_fst <| add_tensor_eq_snd <| smul_tensor_eq <| prod_basisVector_tree _ _]
rw [add_tensor_eq_snd <| add_tensor_eq_fst <| smul_tensor_eq <| prod_basisVector_tree _ _]
rw [add_tensor_eq_snd <| add_tensor_eq_snd <| prod_basisVector_tree _ _]
rw [← add_assoc]
simp only [add_tensor, smul_tensor, tensorNode_tensor]
change _ = basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 0 | 3 => 1)
+- basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 1 | 3 => 0)
+- basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 0 | 3 => 1)
+ basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 1 | 3 => 0)
congr 1
congr 1
congr 1
all_goals
congr
funext x
fin_cases x <;> rfl
lemma leftMetric_mul_rightMetric_tree :
{εL | α α' ⊗ εR | β β'}ᵀ.tensor
= (TensorTree.add (tensorNode
(basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 0 | 3 => 1))) <|
TensorTree.add (TensorTree.smul (-1 : ) (tensorNode
(basisVector leftMetricMulRightMap (fun | 0 => 0 | 1 => 1 | 2 => 1 | 3 => 0)))) <|
TensorTree.add (TensorTree.smul (-1 : ) (tensorNode
(basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 0 | 3 => 1)))) <|
(tensorNode
(basisVector leftMetricMulRightMap (fun | 0 => 1 | 1 => 0 | 2 => 1 | 3 => 0)))).tensor := by
rw [leftMetric_mul_rightMetric]
simp only [Nat.succ_eq_add_one, Nat.reduceAdd, Fin.isValue, add_tensor, tensorNode_tensor,
smul_tensor, neg_smul, one_smul]
rfl
end complexLorentzTensor