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: Mary is a taxi driver if and only if it is raining. If Mary were a taxi driver, then Elisabeth is sleeping. If Elisabeth sleeps, then it is raining.
If Mary were a taxi driver, then it is raining can be inferred via the transitivity rule. If Mary were a taxi driver, then it is raining can be inferred via the biconditional elimination rule. If it rains, then Mary is a taxi driver can be inferred via the biconditional elimination rule.