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: It is not snowing. If Mary were a police officer, then it is snowing. Susan is playing tennis if and only if it is raining. If it rains, then Mary is a police officer.
Mary is not a police officer can be inferred via the modus tollens rule. If it rains, then it is snowing can be inferred via the transitivity rule. If Susan plays tennis, then it is raining can be inferred via the biconditional elimination rule. If it rains, then Susan is playing tennis can be inferred via the biconditional elimination rule.