V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
⊢ t ∈ support (append p p') ↔ t ∈ support p ∨ t ∈ support p'
simp only [mem_support_iff, mem_tail_support_append_iff]
no goals
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
obtain rfl | h := eq_or_ne t v <;> obtain rfl | h' := eq_or_ne t u <;>
  (try have := h'.symm) <;> simp [*]
case inr.inr
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
h : t ≠ v
h' : t ≠ u
this : u ≠ t
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
case inr.inr
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
h : t ≠ v
h' : t ≠ u
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
try have := h'.symm
case inr.inr
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
h : t ≠ v
h' : t ≠ u
this : u ≠ t
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
case inr.inr
V : Type u
V' : Type v
V'' : Type w
G : SimpleGraph V
G' : SimpleGraph V'
G'' : SimpleGraph V''
t u v w : V
p : Walk G u v
p' : Walk G v w
h : t ≠ v
h' : t ≠ u
⊢ t = u ∨ t ∈ List.tail (support p) ∨ t ∈ List.tail (support p') ↔
    (t = u ∨ t ∈ List.tail (support p)) ∨ t = v ∨ t ∈ List.tail (support p')
have := h'.symm