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_2: ~P_1(z_2). exists z_2: Q(z_2) <-> P_1(z_2). forall z_2: Q(z_2) -> R(z_2). forall z_2: R(z_2) -> Q(z_2).
forall z_2: Q(z_2) <-> R(z_2) can be inferred via the universal biconditional introduction rule. forall z_2: R(z_2) <-> Q(z_2) can be inferred via the universal biconditional introduction rule. exists z_2: Q(z_2) -> P_1(z_2) can be inferred via the existential biconditional elimination rule. exists z_2: P_1(z_2) -> Q(z_2) can be inferred via the existential biconditional elimination rule. exists z_2: ~Q(z_2) can be inferred via the existential biconditional elimination rule.