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: It is sunny or it is not raining. If it is late, then it is raining. It is sunny if and only if it is late.
If it rains, then it is sunny can be inferred via the rewriting rule. If it is sunny, then it is late can be inferred via the biconditional elimination rule. If it is late, then it is sunny can be inferred via the biconditional elimination rule.