If PSO J318.5−22 is not both a rogue planet and a planet gravitationally bound by the Sun, then it is a rogue planet.
¬(Planet(pSOJ318.5-22) ∧ Rogue(pSOJ318.5-22) ∧ BoundBy(pSOJ318.5-22, sun, gravitationally)) → (Planet(pSOJ318.5-22) ∧ Rogue(pSOJ318.5-22))