What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Susan is climbing a mountain if and only if Elisabeth is taking a plane. If David were bored, then Elisabeth is taking a plane. If Susan climbs a mountain, then David is bored.
If Susan climbs a mountain, then Elisabeth is taking a plane. If Susan climbs a mountain, then Elisabeth is taking a plane. If Elisabeth takes a plane, then Susan is climbing a mountain.