Consider the following premises. p -> R_19(a_19). s <-> p. forall x_19: ~R_19(x_19). Can we infer ~s or p_3 from them? If possible, name the inference rules being used at each step.
 From forall x_19: ~R_19(x_19) we can infer ~R_19(a_19) via universal instantiation. From p -> R_19(a_19), ~R_19(a_19) we can infer ~p via modus tollens. From s <-> p, ~p we can infer ~s via biconditional elimination. Finally, from ~s we can infer ~s or p_3 via addition. Therefore, the answer is yes.