Theorem: Finmap.union_cancel
File: Mathlib/Data/Finmap.lean

tactic: apply ext_lookup
state_before: α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
⊢ s₁ = s₂
state_after: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
⊢ ∀ (x : α), lookup x s₁ = lookup x s₂

tactic: intro x
state_before: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
⊢ ∀ (x : α), lookup x s₁ = lookup x s₂
state_after: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
⊢ lookup x s₁ = lookup x s₂

tactic: have : (s₁ ∪ s₃).lookup x = (s₂ ∪ s₃).lookup x := h'' ▸ rfl
state_before: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
⊢ lookup x s₁ = lookup x s₂
state_after: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
⊢ lookup x s₁ = lookup x s₂

tactic: by_cases hs₁ : x ∈ s₁
state_before: case a
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
⊢ lookup x s₁ = lookup x s₂
state_after: case pos
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∈ s₁
⊢ lookup x s₁ = lookup x s₂

case neg
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
⊢ lookup x s₁ = lookup x s₂

tactic: rwa [lookup_union_left hs₁, lookup_union_left_of_not_in (h _ hs₁)] at this
state_before: case pos
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∈ s₁
⊢ lookup x s₁ = lookup x s₂
state_after: no goals

tactic: by_cases hs₂ : x ∈ s₂
state_before: case neg
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
⊢ lookup x s₁ = lookup x s₂
state_after: case pos
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
hs₂ : x ∈ s₂
⊢ lookup x s₁ = lookup x s₂

case neg
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
hs₂ : x ∉ s₂
⊢ lookup x s₁ = lookup x s₂

tactic: rwa [lookup_union_left_of_not_in (h' _ hs₂), lookup_union_left hs₂] at this
state_before: case pos
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
hs₂ : x ∈ s₂
⊢ lookup x s₁ = lookup x s₂
state_after: no goals

tactic: rw [lookup_eq_none.mpr hs₁, lookup_eq_none.mpr hs₂]
state_before: case neg
α : Type u
β : α → Type v
inst✝ : DecidableEq α
s₁ s₂ s₃ : Finmap β
h : s₁.Disjoint s₃
h' : s₂.Disjoint s₃
h'' : s₁ ∪ s₃ = s₂ ∪ s₃
x : α
this : lookup x (s₁ ∪ s₃) = lookup x (s₂ ∪ s₃)
hs₁ : x ∉ s₁
hs₂ : x ∉ s₂
⊢ lookup x s₁ = lookup x s₂
state_after: no goals