What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Richard takes a plane, then James is drinking water. James is drinking water if and only if Richard is a politician. Richard is not a politician. If James drinks water, then Richard is taking a plane.
Richard is taking a plane if and only if James is drinking water. James is drinking water if and only if Richard is taking a plane. If James drinks water, then Richard is a politician. If Richard were a politician, then James is drinking water. James is not drinking water.