Consider the following premises. U_1(i_3) <-> S_14(d). ~S(d). forall y_4: U_3(y_4) <-> U_1(y_4). forall x_14: S(x_14) <-> S_14(x_14). Can we infer U_3(i_3) from them? If possible, name the inference rules being used at each step.
 From forall x_14: S(x_14) <-> S_14(x_14) we can infer S(d) <-> S_14(d) via universal instantiation. From forall y_4: U_3(y_4) <-> U_1(y_4) we can infer U_3(i_3) <-> U_1(i_3) via universal instantiation. From S(d) <-> S_14(d), ~S(d) we can infer ~S_14(d) via biconditional elimination. From U_1(i_3) <-> S_14(d), ~S_14(d) we can infer ~U_1(i_3) via biconditional elimination. Finally, from U_3(i_3) <-> U_1(i_3), ~U_1(i_3) we can infer ~U_3(i_3) via biconditional elimination, which contradicts U_3(i_3). Therefore, the answer is no.