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: ~P(x). forall x: U(x) -> Q_3(x). forall x: R(x) <-> P(x). exists x: Q_3(x) -> U(x). forall x: U(x) <-> R(x).
exists x: Q_3(x) <-> U(x) can be inferred via the existential biconditional introduction rule. exists x: U(x) <-> Q_3(x) can be inferred via the existential biconditional introduction rule. forall x: R(x) -> P(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: P(x) -> R(x) can be inferred via the universal biconditional elimination rule. forall x: R(x) -> U(x) can be inferred via the universal biconditional elimination rule. forall x: ~R(x) can be inferred via the universal biconditional elimination rule.