simp [cons_toList, nil_toList, append_toList] at leqn
case cons
V : Type u
E : Type v
inst✝¹ : DecidableEq V
inst✝ : DecidableEq E
G : Graph V E
u✝ v : V
e✝ : EdgeBetween G u✝ v
p' : EdgePath G u✝ v
red' : Reduction (cons e✝ (nil v)) p'
u u' : V
e : EdgeBetween G u u'
p₂ : EdgePath G u v
w✝ : V
h : EdgeBetween G u✝ w✝
t : EdgePath G w✝ u
eqn : cons h (t ++ cons e (cons (EdgeBetween.bar e) p₂)) = cons e✝ (nil v)
leqn : toList (cons h (t ++ cons e (cons (EdgeBetween.bar e) p₂))) = toList (cons e✝ (nil v)) := congrArg toList eqn
⊢ False
no goals