What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Thomas goes running, then Robert is drinking water. Robert is not working. For all z, z will drink water if and only if z will work. Thomas is running if and only if David is taking a plane.
If Thomas goes running, then David is taking a plane. If David takes a plane, then Thomas is running. For all z, if z drinks water, then z is working. For all z, if z works, then z is drinking water.