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: exists z_1: T(z_1) <-> T_2(z_1). forall z_1: T_2(z_1) -> R(z_1). forall z_1: R(z_1) -> T_2(z_1).
forall z_1: T_2(z_1) <-> R(z_1) can be inferred via the universal biconditional introduction rule. forall z_1: R(z_1) <-> T_2(z_1) can be inferred via the universal biconditional introduction rule. exists z_1: T(z_1) -> T_2(z_1) can be inferred via the existential biconditional elimination rule. exists z_1: T_2(z_1) -> T(z_1) can be inferred via the existential biconditional elimination rule.