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: U(a_12) <-> S_12(a_12). ~U(a_12). forall x_12: U(x_12) -> S_12(x_12).
U(a_12) -> S_12(a_12) can be inferred via the biconditional elimination rule. S_12(a_12) -> U(a_12) can be inferred via the biconditional elimination rule.