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 y_1, y_1 will play tennis. For all y_1, y_1 is not a nurse or y_1 will play squash. For all y_1, y_1 will not play tennis or y_1 will drink water. For all y_1, y_1 will not drink water or y_1 is a bartender.
Nothing can be inferred from these premises.