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: U_3(a_7) -> ~S(b). forall x_7: U_3(x_7) <-> S_7(x_7). forall y: S(y).
forall x_7: U_3(x_7) -> S_7(x_7) can be inferred via the universal biconditional elimination rule. forall x_7: S_7(x_7) -> U_3(x_7) can be inferred via the universal biconditional elimination rule.