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_7: P_4(x_7) <-> U(x_7). forall x_7: R(x_7) -> P_4(x_7). exists x_7: ~P_7(x_7) or R(x_7). forall x_7: P_7(x_7) or U(x_7).
exists x_7: U(x_7) or R(x_7) can be inferred via the existential resolution rule. forall x_7: P_4(x_7) -> U(x_7) can be inferred via the universal biconditional elimination rule. forall x_7: U(x_7) -> P_4(x_7) can be inferred via the universal biconditional elimination rule.