What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Robert were a nurse, then James is a bartender. If James were a bartender, then Robert is a nurse. If Robert were a nurse, then James is a bartender.
Robert is a nurse if and only if James is a bartender. James is a bartender if and only if Robert is a nurse. James is a bartender if and only if Robert is a nurse. Robert is a nurse if and only if James is a bartender.