Consider the following premises. s_2 <-> q_7. ~s_2. u_4 <-> R_23(d). forall x_23: ~R_23(x_23). Can we infer q_7 from them? If possible, name the inference rules being used at each step.
 From forall x_23: ~R_23(x_23) we can infer ~R_23(d) via universal instantiation. From u_4 <-> R_23(d), ~R_23(d) we can infer ~u_4 via biconditional elimination. Finally, from s_2 <-> q_7, ~s_2 we can infer ~q_7 via biconditional elimination, which contradicts q_7. Therefore, the answer is no.