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: ~S_15(a_15). forall x_15: R_15(x_15) -> S_15(x_15). R_15(a_15) <-> q_9.
R_15(a_15) -> q_9 can be inferred via the biconditional elimination rule. q_9 -> R_15(a_15) can be inferred via the biconditional elimination rule.