Consider the following premises. ~p_2. ~S_11(a_11). s -> p_2. forall x_11: R_11(x_11) <-> S_11(x_11). Can we infer R_11(a_11) from them? If possible, name the inference rules being used at each step.
 From s -> p_2, ~p_2 we can infer ~s via modus tollens. From forall x_11: R_11(x_11) <-> S_11(x_11) we can infer R_11(a_11) <-> S_11(a_11) via universal instantiation. Finally, from R_11(a_11) <-> S_11(a_11), ~S_11(a_11) we can infer ~R_11(a_11) via biconditional elimination, which contradicts R_11(a_11). Therefore, the answer is no.