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_8: P_8(x_8) -> Q_8(x_8). Q_8(d_1) <-> w. ~w. forall x_8: Q_8(x_8) -> P_8(x_8).
Q_8(d_1) -> w can be inferred via the biconditional elimination rule. w -> Q_8(d_1) can be inferred via the biconditional elimination rule. ~Q_8(d_1) can be inferred via the biconditional elimination rule. forall x_8: P_8(x_8) <-> Q_8(x_8) can be inferred via the universal biconditional introduction rule. forall x_8: Q_8(x_8) <-> P_8(x_8) can be inferred via the universal biconditional introduction rule.