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 David were poor, then it is raining. It is late or it is cold. It is raining if and only if it is cold. It is not late or David is poor.
It is cold or David is poor can be inferred via the resolution rule. If it rains, then it is cold can be inferred via the biconditional elimination rule. If it is cold, then it is raining can be inferred via the biconditional elimination rule.