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_1, x_1 will not sleep. For all x_1, x_1 is an office clerk if and only if x_1 will play tennis. For all x_1, if x_1 plays tennis, then x_1 is sleeping.
For all x_1, x_1 will not play tennis can be inferred via the universal modus tollens rule. For all x_1, if x_1 were an office clerk, then x_1 is playing tennis can be inferred via the universal biconditional elimination rule. For all x_1, if x_1 plays tennis, then x_1 is an office clerk can be inferred via the universal biconditional elimination rule.