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_5, x_5 is not a nurse. For all x_5, x_5 is a janitor. For all x_5, x_5 is a nurse if and only if x_5 is a janitor.
Since the premises are contradictory, we can infer anything from them.