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