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_4, x_4 is not a taxi driver. It is raining if and only if Barbara is a taxi driver. It is cloudy.
If it rains, then Barbara is a taxi driver can be inferred via the biconditional elimination rule. If Barbara were a taxi driver, then it is raining can be inferred via the biconditional elimination rule.