Consider the following premises. forall x_14: ~R_14(x_14). u <-> R_14(a_14). Can we infer u from them? If possible, name the inference rules being used at each step.
 From forall x_14: ~R_14(x_14) we can infer ~R_14(a_14) via universal instantiation. Finally, from u <-> R_14(a_14), ~R_14(a_14) we can infer ~u via biconditional elimination, which contradicts u. Therefore, the answer is no.