Module: Mathlib.AlgebraicTopology.SimplexCategory.GeneratorsRelations.NormalForms

Goal state before:
pp: case pos
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : hL.head.castSucc < t
h₂ : a < ↑t
⊢ ↑(t.pred ⋯) = ↑t - 1

pp: case neg
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : hL.head.castSucc < t
h₂ : ¬a < ↑t
⊢ ↑(t.pred ⋯) = ↑t

pp: case pos
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : ¬hL.head.castSucc < t
h₂ : a < ↑t
⊢ ↑(t.castPred ⋯) = ↑t - 1

pp: case neg
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : ¬hL.head.castSucc < t
h₂ : ¬a < ↑t
⊢ ↑(t.castPred ⋯) = ↑t

Tactic:
· rfl

Goal state after:
case neg
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : hL.head.castSucc < t
h₂ : ¬a < ↑t
⊢ ↑(t.pred ⋯) = ↑t

case pos
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : ¬hL.head.castSucc < t
h₂ : a < ↑t
⊢ ↑(t.castPred ⋯) = ↑t - 1

case neg
L✝ : List ℕ
j a : ℕ
L : List ℕ
h_rec :
  ∀ (m₁ m₂ : ℕ),
    IsAdmissible m₂ L →
      ∀ (hk : m₂ + L.length = m₁) (hj : j < m₁ + 1),
        ↑((SimplexCategory.Hom.toOrderHom (toSimplexCategory.map (standardσ L hk))) ⟨j, hj⟩) = simplicialEvalσ L j
m₂ : ℕ
hL : IsAdmissible m₂ (a :: L)
hj : j < m₂ + (L.length + 1) + 1
a₀ : Fin (m₂ + 1) := hL.head
t : Fin (m₂ + 2)
h₁ : ¬hL.head.castSucc < t
h₂ : ¬a < ↑t
⊢ ↑(t.castPred ⋯) = ↑t