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 x: P_4(x) or ~R(x). forall x: R(x) <-> U_1(x). forall x: ~P_4(x).
exists x: R(x) -> P_4(x) can be inferred via the existential rewriting rule. forall x: R(x) -> U_1(x) can be inferred via the universal biconditional elimination rule. forall x: U_1(x) -> R(x) can be inferred via the universal biconditional elimination rule.