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 will sleep or x_9 is a janitor. There is at least one x_9 for which if x_9 were a musician, then x_9 is not driving a car. For all x_9, if x_9 sleeps, then x_9 is driving a car. For all x_9, if x_9 drives a car, then x_9 is sleeping. For all x_9, if x_9 were a janitor, then x_9 is driving a car.
For all x_9, if x_9 were a janitor, then x_9 is sleeping can be inferred via the universal transitivity rule. For all x_9, x_9 will drive a car can be inferred via the universal disjunction elimination rule. For all x_9, x_9 will sleep if and only if x_9 will drive a car can be inferred via the universal biconditional introduction rule. For all x_9, x_9 will drive a car if and only if x_9 will sleep can be inferred via the universal biconditional introduction rule.