Consider the following premises. ~S_11(a_11). w -> q_13. forall x_11: P(x_11) <-> S_11(x_11). ~q_13. Can we infer P(a_11) from them?
 From w -> q_13, ~q_13 we can infer ~w. From forall x_11: P(x_11) <-> S_11(x_11) we can infer P(a_11) <-> S_11(a_11). Finally, from P(a_11) <-> S_11(a_11), ~S_11(a_11) we can infer ~P(a_11), which contradicts P(a_11). Therefore, the answer is no.