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: If Robert were a janitor, then it is not raining. It is raining. Jennifer is excited or Richard is cooking. It is cloudy. Robert is a janitor if and only if Jennifer is excited.
Robert is not a janitor can be inferred via the modus tollens rule. It is raining and it is cloudy can be inferred via the conjunction rule. It is cloudy and it is raining can be inferred via the conjunction rule. If Robert were a janitor, then Jennifer is excited can be inferred via the biconditional elimination rule. If Jennifer were excited, then Robert is a janitor can be inferred via the biconditional elimination rule.