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: Q(x) <-> R_1(x). forall x: R_1(x) -> Q(x). forall x: ~Q(x).
forall x: ~R_1(x) can be inferred via the universal modus tollens rule. forall x: Q(x) -> R_1(x) can be inferred via the universal biconditional elimination rule. forall x: R_1(x) -> Q(x) can be inferred via the universal biconditional elimination rule. forall x: ~R_1(x) can be inferred via the universal biconditional elimination rule.