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_16: U_4(x_16) -> Q_16(x_16). forall x_16: P_15(x_16) or Q_15(x_16). forall x_16: Q_16(x_16) -> U_4(x_16). forall x_16: ~P_15(x_16) or U_4(x_16). exists x_16: ~Q_15(x_16).
forall x_16: Q_15(x_16) or U_4(x_16) can be inferred via the universal resolution rule. forall x_16: U_4(x_16) <-> Q_16(x_16) can be inferred via the universal biconditional introduction rule. forall x_16: Q_16(x_16) <-> U_4(x_16) can be inferred via the universal biconditional introduction rule.