right
Node : Type
inst : DecidableEq Node
g : Graph Node
xs ys : List Node
x✝ x : Node
c1 : x ∈ ys
⊢ x ∈ reachable_from_list g xs ∨ x ∈ reachable_from_list g ys
case h
Node : Type
inst : DecidableEq Node
g : Graph Node
xs ys : List Node
x✝ x : Node
c1 : x ∈ ys
⊢ x ∈ reachable_from_list g ys