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 not climb a mountain. For all x_9, x_9 is a cashier. For all x_9, x_9 will climb a mountain if and only if x_9 is a cashier.
Since the premises are contradictory, we can infer anything from them.