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 y_4, if y_4 drives a car, then y_4 is a carpenter. For all y_4, if y_4 plays squash, then y_4 is a carpenter. For all y_4, if y_4 were a carpenter, then y_4 is driving a car. For all y_4, y_4 will not drive a car.
For all y_4, y_4 is not a carpenter can be inferred via the universal modus tollens rule. For all y_4, if y_4 plays squash, then y_4 is driving a car can be inferred via the universal transitivity rule. For all y_4, y_4 will drive a car if and only if y_4 is a carpenter can be inferred via the universal biconditional introduction rule. For all y_4, y_4 is a carpenter if and only if y_4 will drive a car can be inferred via the universal biconditional introduction rule.