Consider the following premises. forall x_11: R_11(x_11) <-> S_11(x_11). ~S_11(a_11). Can we infer R_11(a_11) from them? If possible, name the inference rules being used at each step.
 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.