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 z_1: U_4(z_1) -> P(z_1). forall z_1: P(z_1) -> U_4(z_1). forall z_1: U_4(z_1) or T(z_1). forall z_1: ~P(z_1).
forall z_1: ~U_4(z_1) can be inferred via the universal modus tollens rule. forall z_1: U_4(z_1) <-> P(z_1) can be inferred via the universal biconditional introduction rule. forall z_1: P(z_1) <-> U_4(z_1) can be inferred via the universal biconditional introduction rule.