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_18, x_18 will play tennis or x_18 will go running. For all x_18, x_18 will play tennis if and only if x_18 is a janitor. For all x_18, x_18 is not a janitor.
For all x_18, if x_18 plays tennis, then x_18 is a janitor can be inferred via the universal biconditional elimination rule. For all x_18, if x_18 were a janitor, then x_18 is playing tennis can be inferred via the universal biconditional elimination rule. For all x_18, x_18 will not play tennis can be inferred via the universal biconditional elimination rule.