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 it is late, then it is raining. It is raining if and only if it is late. If it rains, then it is late.
It is late if and only if it is raining can be inferred via the biconditional introduction rule. It is raining if and only if it is late can be inferred via the biconditional introduction rule. If it rains, then it is late can be inferred via the biconditional elimination rule. If it is late, then it is raining can be inferred via the biconditional elimination rule.