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 Michael were a janitor, then it is cold. It is not cold. If Michael were not a janitor, then William is a lawyer. If it is cold, then Michael is a janitor.
Michael is not a janitor can be inferred via the modus tollens rule. Michael is a janitor if and only if it is cold can be inferred via the biconditional introduction rule. It is cold if and only if Michael is a janitor can be inferred via the biconditional introduction rule.