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: William is sleeping or Richard is a nurse. If Richard were a nurse, then William is a janitor. For all x_7, x_7 is a janitor if and only if x_7 will sleep.
For all x_7, if x_7 were a janitor, then x_7 is sleeping can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 sleeps, then x_7 is a janitor can be inferred via the universal biconditional elimination rule.