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. forall x_14: Q_14(x_14) -> U_2(x_14). ~U_2(a_13). forall x_14: U_2(x_14) -> Q_14(x_14).
u and ~U_2(a_13) can be inferred via the conjunction rule. ~U_2(a_13) and u can be inferred via the conjunction rule. forall x_14: Q_14(x_14) <-> U_2(x_14) can be inferred via the universal biconditional introduction rule. forall x_14: U_2(x_14) <-> Q_14(x_14) can be inferred via the universal biconditional introduction rule.