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 Richard were an electrician, then Jennifer is not cooking. For all x, if x were an electrician, then x is a janitor. Robert is driving a car. For all x, if x were a janitor, then x is an electrician. If Robert drives a car, then Jennifer is cooking.
Jennifer is cooking can be inferred via the modus ponens rule. For all x, x is an electrician if and only if x is a janitor can be inferred via the universal biconditional introduction rule. For all x, x is a janitor if and only if x is an electrician can be inferred via the universal biconditional introduction rule.