What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Karen is not taking a plane. Charles is working if and only if Karen is taking a plane. If Thomas climbs a mountain, then Charles is working. If Charles works, then Thomas is climbing a mountain.
Thomas is climbing a mountain if and only if Charles is working. Charles is working if and only if Thomas is climbing a mountain. If Charles works, then Karen is taking a plane. If Karen takes a plane, then Charles is working. Charles is not working.