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: William is not a soldier. Richard is listening to a song if and only if William is a soldier. If it snows, then Richard is listening to a song. Robert is a doctor.
William is not a soldier and Robert is a doctor can be inferred via the conjunction rule. Robert is a doctor and William is not a soldier can be inferred via the conjunction rule. If Richard listens to a song, then William is a soldier can be inferred via the biconditional elimination rule. If William were a soldier, then Richard is listening to a song can be inferred via the biconditional elimination rule. Richard is not listening to a song can be inferred via the biconditional elimination rule.