Consider the following premises. forall x_8: R_8(x_8) or S_8(x_8). p <-> S_8(c_2). R_8(c_2) -> p. Can we infer ~p from them?
 From forall x_8: R_8(x_8) or S_8(x_8) we can infer R_8(c_2) or S_8(c_2). From p <-> S_8(c_2) we can infer S_8(c_2) -> p. Finally, from R_8(c_2) -> p, S_8(c_2) -> p, R_8(c_2) or S_8(c_2) we can infer p, which contradicts ~p. Therefore, the answer is no.