intro x a1
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
xs : List Node
⊢ ∀ x ∈ reachable_from_list g (list_direct_succ_list g xs), x ∈ reachable_from_list g xs
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
xs : List Node
x : Node
a1 : x ∈ reachable_from_list g (list_direct_succ_list g xs)
⊢ x ∈ reachable_from_list g xs