simp only [reachable_from_list_of_cons g hd tl]
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
x hd : Node
tl : List Node
ih : x ∈ reachable_from_list g (list_direct_succ_list g tl) → x ∈ reachable_from_list g tl
a1 : x ∈ reachable_from_list g (direct_succ_list g hd ++ list_direct_succ_list g tl)
⊢ x ∈ reachable_from_list g (hd :: tl)
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
x hd : Node
tl : List Node
ih : x ∈ reachable_from_list g (list_direct_succ_list g tl) → x ∈ reachable_from_list g tl
a1 : x ∈ reachable_from_list g (direct_succ_list g hd ++ list_direct_succ_list g tl)
⊢ x ∈ reachable_from_list g [hd] ∪ reachable_from_list g tl