Module: Mathlib.Topology.Homotopy.Lifting

Goal state before:
pp: case refine_1
E : Type u_1
X : Type u_2
A : Type u_3
inst✝⁴ : TopologicalSpace E
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace A
inst✝¹ : PathConnectedSpace A
inst✝ : LocallyPathConnectedSpace A
f : C(A, X)
a₀ : A
e₀ : E
Γ : (γ : C(↑I, A)) → γ 0 = a₀ → C(↑I, E)
Γ_0 : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), (Γ γ a) 0 = e₀
F : A → E := fun a ↦ (Γ (somePath a₀ a).toContinuousMap ⋯) 1
a : A
p : OpenPartialHomeomorph E X
hep : F a ∈ p.source
homeo : IsLocalHomeomorph ↑p
he : ↑p e₀ = f a₀
uniq :
  ∀ (γ γ' : C(↑I, A)) (Γ Γ' : C(↑I, E)),
    γ 0 = a₀ →
      γ' 0 = a₀ → Γ 0 = e₀ → Γ' 0 = e₀ → ↑p ∘ ⇑Γ = ⇑(f.comp γ) → ↑p ∘ ⇑Γ' = ⇑(f.comp γ') → γ 1 = γ' 1 → Γ 1 = Γ' 1
Γ_lifts : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), ↑p ∘ ⇑(Γ γ a) = ⇑(f.comp γ)
this : ∀ (a : A), ↑p (F a) = f a
hfap : f a ∈ p.target
U : Set A
haU : U ∈ 𝓝 a
U_conn : IsPathConnected U
hUp : id U ⊆ ⇑f ⁻¹' p.target
x : A
hxU : x ∈ U
γ : Path a x
hγ : ∀ (t : ↑I), γ t ∈ U
Γ' : Path e₀ ((↑p.symm ∘ ⇑f) a) :=
  { toContinuousMap := Γ (somePath a₀ a).toContinuousMap ⋯, source' := ⋯, target' := ⋯ }
x✝ : ↑I
⊢ ↑p (if h : ↑x✝ ≤ 1 / 2 then Γ' ⟨2 * ↑x✝, ⋯⟩ else (γ.map' ⋯) ⟨2 * ↑x✝ - 1, ⋯⟩) =
    f (if h : ↑x✝ ≤ 1 / 2 then (somePath a₀ a) ⟨2 * ↑x✝, ⋯⟩ else γ ⟨2 * ↑x✝ - 1, ⋯⟩)

Tactic:
split_ifs

Goal state after:
case pos
E : Type u_1
X : Type u_2
A : Type u_3
inst✝⁴ : TopologicalSpace E
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace A
inst✝¹ : PathConnectedSpace A
inst✝ : LocallyPathConnectedSpace A
f : C(A, X)
a₀ : A
e₀ : E
Γ : (γ : C(↑I, A)) → γ 0 = a₀ → C(↑I, E)
Γ_0 : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), (Γ γ a) 0 = e₀
F : A → E := fun a ↦ (Γ (somePath a₀ a).toContinuousMap ⋯) 1
a : A
p : OpenPartialHomeomorph E X
hep : F a ∈ p.source
homeo : IsLocalHomeomorph ↑p
he : ↑p e₀ = f a₀
uniq :
  ∀ (γ γ' : C(↑I, A)) (Γ Γ' : C(↑I, E)),
    γ 0 = a₀ →
      γ' 0 = a₀ → Γ 0 = e₀ → Γ' 0 = e₀ → ↑p ∘ ⇑Γ = ⇑(f.comp γ) → ↑p ∘ ⇑Γ' = ⇑(f.comp γ') → γ 1 = γ' 1 → Γ 1 = Γ' 1
Γ_lifts : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), ↑p ∘ ⇑(Γ γ a) = ⇑(f.comp γ)
this : ∀ (a : A), ↑p (F a) = f a
hfap : f a ∈ p.target
U : Set A
haU : U ∈ 𝓝 a
U_conn : IsPathConnected U
hUp : id U ⊆ ⇑f ⁻¹' p.target
x : A
hxU : x ∈ U
γ : Path a x
hγ : ∀ (t : ↑I), γ t ∈ U
Γ' : Path e₀ ((↑p.symm ∘ ⇑f) a) :=
  { toContinuousMap := Γ (somePath a₀ a).toContinuousMap ⋯, source' := ⋯, target' := ⋯ }
x✝ : ↑I
h✝ : ↑x✝ ≤ 1 / 2
⊢ ↑p (Γ' ⟨2 * ↑x✝, ⋯⟩) = f ((somePath a₀ a) ⟨2 * ↑x✝, ⋯⟩)

case neg
E : Type u_1
X : Type u_2
A : Type u_3
inst✝⁴ : TopologicalSpace E
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace A
inst✝¹ : PathConnectedSpace A
inst✝ : LocallyPathConnectedSpace A
f : C(A, X)
a₀ : A
e₀ : E
Γ : (γ : C(↑I, A)) → γ 0 = a₀ → C(↑I, E)
Γ_0 : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), (Γ γ a) 0 = e₀
F : A → E := fun a ↦ (Γ (somePath a₀ a).toContinuousMap ⋯) 1
a : A
p : OpenPartialHomeomorph E X
hep : F a ∈ p.source
homeo : IsLocalHomeomorph ↑p
he : ↑p e₀ = f a₀
uniq :
  ∀ (γ γ' : C(↑I, A)) (Γ Γ' : C(↑I, E)),
    γ 0 = a₀ →
      γ' 0 = a₀ → Γ 0 = e₀ → Γ' 0 = e₀ → ↑p ∘ ⇑Γ = ⇑(f.comp γ) → ↑p ∘ ⇑Γ' = ⇑(f.comp γ') → γ 1 = γ' 1 → Γ 1 = Γ' 1
Γ_lifts : ∀ (γ : C(↑I, A)) (a : γ 0 = a₀), ↑p ∘ ⇑(Γ γ a) = ⇑(f.comp γ)
this : ∀ (a : A), ↑p (F a) = f a
hfap : f a ∈ p.target
U : Set A
haU : U ∈ 𝓝 a
U_conn : IsPathConnected U
hUp : id U ⊆ ⇑f ⁻¹' p.target
x : A
hxU : x ∈ U
γ : Path a x
hγ : ∀ (t : ↑I), γ t ∈ U
Γ' : Path e₀ ((↑p.symm ∘ ⇑f) a) :=
  { toContinuousMap := Γ (somePath a₀ a).toContinuousMap ⋯, source' := ⋯, target' := ⋯ }
x✝ : ↑I
h✝ : ¬↑x✝ ≤ 1 / 2
⊢ ↑p ((γ.map' ⋯) ⟨2 * ↑x✝ - 1, ⋯⟩) = f (γ ⟨2 * ↑x✝ - 1, ⋯⟩)