What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_19, x_19 is not a police officer. Charles is working if and only if William is climbing a mountain. Barbara is a police officer if and only if Charles is working.
If Charles works, then William is climbing a mountain. If Barbara were a police officer, then Charles is working. If William climbs a mountain, then Charles is working. If Charles works, then Barbara is a police officer.