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 y_1: S(y_1) or P_4(y_1). forall y_1: U_4(y_1) <-> P_2(y_1). forall y_1: P_2(y_1) <-> S(y_1). forall y_1: ~U_4(y_1).
forall y_1: U_4(y_1) -> P_2(y_1) can be inferred via the universal biconditional elimination rule. forall y_1: P_2(y_1) -> S(y_1) can be inferred via the universal biconditional elimination rule. forall y_1: P_2(y_1) -> U_4(y_1) can be inferred via the universal biconditional elimination rule. forall y_1: S(y_1) -> P_2(y_1) can be inferred via the universal biconditional elimination rule. forall y_1: ~P_2(y_1) can be inferred via the universal biconditional elimination rule.