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: forall x_10: U(x_10) -> S_10(x_10). ~S_10(a_10). r <-> U(a_10).
r -> U(a_10) can be inferred via the biconditional elimination rule. U(a_10) -> r can be inferred via the biconditional elimination rule.