Theorem: contractLeft_assoc_coevaluation'
File: Mathlib/LinearAlgebra/Coevaluation.lean

Proof steps:
state_before: K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
⊢ LinearMap.lTensor V (contractLeft K V) ∘ₗ
      ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V) =
    ↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V)
state_after: K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ LinearMap.lTensor V (contractLeft K V) ∘ₗ
      ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V) =
    ↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V)
tactic: letI := Classical.decEq (Basis.ofVectorSpaceIndex K V)
state_before: K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ LinearMap.lTensor V (contractLeft K V) ∘ₗ
      ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V) =
    ↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V)
state_after: case H
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ (mk K K V).compr₂
      (LinearMap.lTensor V (contractLeft K V) ∘ₗ
        ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)) =
    (mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))
tactic: apply TensorProduct.ext
state_before: case H
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ (mk K K V).compr₂
      (LinearMap.lTensor V (contractLeft K V) ∘ₗ
        ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)) =
    (mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ ((mk K K V).compr₂
        (LinearMap.lTensor V (contractLeft K V) ∘ₗ
          ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
      1 =
    ((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1
tactic: apply LinearMap.ext_ring
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ ((mk K K V).compr₂
        (LinearMap.lTensor V (contractLeft K V) ∘ₗ
          ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
      1 =
    ((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∀ (i : ↑(Basis.ofVectorSpaceIndex K V)),
    (((mk K K V).compr₂
            (LinearMap.lTensor V (contractLeft K V) ∘ₗ
              ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
          1)
        ((Basis.ofVectorSpace K V) i) =
      (((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1) ((Basis.ofVectorSpace K V) i)
tactic: apply (Basis.ofVectorSpace K V).ext
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∀ (i : ↑(Basis.ofVectorSpaceIndex K V)),
    (((mk K K V).compr₂
            (LinearMap.lTensor V (contractLeft K V) ∘ₗ
              ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
          1)
        ((Basis.ofVectorSpace K V) i) =
      (((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1) ((Basis.ofVectorSpace K V) i)
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (((mk K K V).compr₂
          (LinearMap.lTensor V (contractLeft K V) ∘ₗ
            ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
        1)
      ((Basis.ofVectorSpace K V) j) =
    (((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1) ((Basis.ofVectorSpace K V) j)
tactic: intro j
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (((mk K K V).compr₂
          (LinearMap.lTensor V (contractLeft K V) ∘ₗ
            ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V)))
        1)
      ((Basis.ofVectorSpace K V) j) =
    (((mk K K V).compr₂ (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V))) 1) ((Basis.ofVectorSpace K V) j)
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V) ∘ₗ
        ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V))
      (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j)
tactic: rw [LinearMap.compr₂_apply, LinearMap.compr₂_apply, TensorProduct.mk_apply]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V) ∘ₗ
        ↑(TensorProduct.assoc K V (Module.Dual K V) V) ∘ₗ LinearMap.rTensor V (coevaluation K V))
      (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (↑(TensorProduct.rid K V).symm ∘ₗ ↑(TensorProduct.lid K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j)
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((LinearMap.rTensor V (coevaluation K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))) =
    (TensorProduct.rid K V).symm ((TensorProduct.lid K V) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))
tactic: simp only [LinearMap.coe_comp, Function.comp_apply, LinearEquiv.coe_toLinearMap]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((LinearMap.rTensor V (coevaluation K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))) =
    (TensorProduct.rid K V).symm ((TensorProduct.lid K V) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((LinearMap.rTensor V (coevaluation K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: rw [lid_tmul, one_smul, rid_symm_apply]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((LinearMap.rTensor V (coevaluation K V)) (1 ⊗ₜ[K] (Basis.ofVectorSpace K V) j))) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((∑ i : ↑(Basis.ofVectorSpaceIndex K V),
            (Basis.ofVectorSpace K V) i ⊗ₜ[K] (Basis.ofVectorSpace K V).coord i) ⊗ₜ[K]
          (Basis.ofVectorSpace K V) j)) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: simp only [LinearEquiv.coe_toLinearMap, LinearMap.rTensor_tmul, coevaluation_apply_one]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      ((TensorProduct.assoc K V (Module.Dual K V) V)
        ((∑ i : ↑(Basis.ofVectorSpaceIndex K V),
            (Basis.ofVectorSpace K V) i ⊗ₜ[K] (Basis.ofVectorSpace K V).coord i) ⊗ₜ[K]
          (Basis.ofVectorSpace K V) j)) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      (∑ x : ↑(Basis.ofVectorSpaceIndex K V),
        (TensorProduct.assoc K V (Module.Dual K V) V)
          (((Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x) ⊗ₜ[K] (Basis.ofVectorSpace K V) j)) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: rw [TensorProduct.sum_tmul, map_sum]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      (∑ x : ↑(Basis.ofVectorSpaceIndex K V),
        (TensorProduct.assoc K V (Module.Dual K V) V)
          (((Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x) ⊗ₜ[K] (Basis.ofVectorSpace K V) j)) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      (∑ x : ↑(Basis.ofVectorSpaceIndex K V),
        (Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: simp only [assoc_tmul]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (LinearMap.lTensor V (contractLeft K V))
      (∑ x : ↑(Basis.ofVectorSpaceIndex K V),
        (Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∑ x : ↑(Basis.ofVectorSpaceIndex K V),
      (LinearMap.lTensor V (contractLeft K V))
        ((Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: rw [map_sum]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∑ x : ↑(Basis.ofVectorSpaceIndex K V),
      (LinearMap.lTensor V (contractLeft K V))
        ((Basis.ofVectorSpace K V) x ⊗ₜ[K] (Basis.ofVectorSpace K V).coord x ⊗ₜ[K] (Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∑ x : ↑(Basis.ofVectorSpaceIndex K V),
      (Basis.ofVectorSpace K V) x ⊗ₜ[K] ((Basis.ofVectorSpace K V).coord x) ((Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: simp only [LinearMap.lTensor_tmul, contractLeft_apply]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ ∑ x : ↑(Basis.ofVectorSpaceIndex K V),
      (Basis.ofVectorSpace K V) x ⊗ₜ[K] ((Basis.ofVectorSpace K V).coord x) ((Basis.ofVectorSpace K V) j) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (∑ x : ↑(Basis.ofVectorSpaceIndex K V), if j = x then (Basis.ofVectorSpace K V) x ⊗ₜ[K] 1 else 0) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: simp only [Basis.coord_apply, Basis.repr_self_apply, TensorProduct.tmul_ite]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (∑ x : ↑(Basis.ofVectorSpaceIndex K V), if j = x then (Basis.ofVectorSpace K V) x ⊗ₜ[K] 1 else 0) =
    (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (if j ∈ Finset.univ then (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1 else 0) = (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
tactic: rw [Finset.sum_ite_eq]
state_before: case H.h
K : Type u
inst✝³ : Field K
V : Type v
inst✝² : AddCommGroup V
inst✝¹ : Module K V
inst✝ : FiniteDimensional K V
this : DecidableEq ↑(Basis.ofVectorSpaceIndex K V) := Classical.decEq ↑(Basis.ofVectorSpaceIndex K V)
j : ↑(Basis.ofVectorSpaceIndex K V)
⊢ (if j ∈ Finset.univ then (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1 else 0) = (Basis.ofVectorSpace K V) j ⊗ₜ[K] 1
state_after: no goals
tactic: simp only [Finset.mem_univ, if_true]