What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_9, x_9 is a janitor or x_9 will not take a plane. For all x_9, x_9 will take a plane or x_9 is not a janitor.
For all x_9, if x_9 takes a plane, then x_9 is a janitor can be inferred via the universal rewriting rule. For all x_9, if x_9 were a janitor, then x_9 is taking a plane can be inferred via the universal rewriting rule.