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_17: ~R_17(x_17). u or q_4. u <-> R_17(a_17).
u -> R_17(a_17) can be inferred via the biconditional elimination rule. R_17(a_17) -> u can be inferred via the biconditional elimination rule.