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_9: U_1(x_9) or T_3(x_9). forall x_9: U_1(x_9) <-> P(x_9). forall x_9: P(x_9) -> T_3(x_9). forall x_9: T_3(x_9) -> P(x_9).
forall x_9: P(x_9) <-> T_3(x_9) can be inferred via the universal biconditional introduction rule. forall x_9: T_3(x_9) <-> P(x_9) can be inferred via the universal biconditional introduction rule. forall x_9: U_1(x_9) -> P(x_9) can be inferred via the universal biconditional elimination rule. forall x_9: P(x_9) -> U_1(x_9) can be inferred via the universal biconditional elimination rule.