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 y_2: U(y_2) -> S_1(y_2). forall y_2: S_1(y_2) <-> U(y_2). ~U(a_2).
forall y_2: S_1(y_2) -> U(y_2) can be inferred via the universal biconditional elimination rule. forall y_2: U(y_2) -> S_1(y_2) can be inferred via the universal biconditional elimination rule.