What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, if y climbs a mountain, then y is driving a car. For all y, if y drives a car, then y is climbing a mountain. For all y, y will climb a mountain if and only if y will drive a car.
For all y, y will climb a mountain if and only if y will drive a car. For all y, y will drive a car if and only if y will climb a mountain. For all y, if y climbs a mountain, then y is driving a car. For all y, if y drives a car, then y is climbing a mountain.