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: U(x) -> R_1(x). ~R_1(a_7). r_4 -> U(a_7). forall x: R_1(x) -> U(x).
forall x: U(x) <-> R_1(x) can be inferred via the universal biconditional introduction rule. forall x: R_1(x) <-> U(x) can be inferred via the universal biconditional introduction rule.