tauto
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
visited : List Node
x : Node
stack : List Node
c1 : x ∉ visited
s1 : ∀ x_1 ∈ reachable_from_list g (direct_succ_list g x), x_1 ∈ reachable_from_list g [x]
ih :
  ∀ x_1 ∈ dft_aux g (direct_succ_list g x ++ stack) (x :: visited),
    x_1 = x ∨ (x_1 ∈ reachable_from_list g (direct_succ_list g x) ∨ x_1 ∈ reachable_from_list g stack) ∨ x_1 ∈ visited
⊢ ((x ∈ reachable_from_list g [x] ∨ x ∈ reachable_from_list g stack) ∨ x ∈ visited) ∧
    ∀ (a : Node),
      (a ∈ reachable_from_list g (direct_succ_list g x) ∨ a ∈ reachable_from_list g stack) ∨ a ∈ visited →
        (a ∈ reachable_from_list g [x] ∨ a ∈ reachable_from_list g stack) ∨ a ∈ visited
no goals