What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If Richard were an artist, then Linda is listening to a song. Linda is not listening to a song. If Linda listens to a song, then Charles is a doctor. Richard is an artist if and only if Charles is a doctor.
Richard is not an artist can be inferred via the modus tollens rule. If Richard were an artist, then Charles is a doctor can be inferred via the transitivity rule. If Richard were an artist, then Charles is a doctor can be inferred via the biconditional elimination rule. If Charles were a doctor, then Richard is an artist can be inferred via the biconditional elimination rule.