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_7: R(x_7). forall x_7: S_4(x_7) -> ~R(x_7). S_4(a_5) <-> q.
S_4(a_5) -> q can be inferred via the biconditional elimination rule. q -> S_4(a_5) can be inferred via the biconditional elimination rule. forall x_7: ~S_4(x_7) can be inferred via the universal modus tollens rule.