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: ~R(x). forall x: U_4(x) -> W(x). forall x: R(x) <-> U(x). forall x: U(x) -> U_4(x). exists x: W(x) -> U(x).
forall x: U(x) -> W(x) can be inferred via the universal transitivity rule. exists x: W(x) -> U_4(x) can be inferred via the existential transitivity rule. exists x: U_4(x) -> U(x) can be inferred via the existential transitivity rule. forall x: R(x) -> U(x) can be inferred via the universal biconditional elimination rule. forall x: U(x) -> R(x) can be inferred via the universal biconditional elimination rule. forall x: ~U(x) can be inferred via the universal biconditional elimination rule.