What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Mary is listening to a song if and only if Robert is a sailor. Linda is cooking. Robert is not a sailor.
Linda is cooking and Robert is not a sailor. Robert is not a sailor and Linda is cooking. If Mary listens to a song, then Robert is a sailor. If Robert were a sailor, then Mary is listening to a song. Mary is not listening to a song.