Consider the following premises. forall x_15: R_15(x_15) -> S_15(x_15). t_4 -> r_4. S_15(a_15) -> t_4. s -> R_15(a_15). Can we infer s -> r_4 from them? If possible, name the inference rules being used at each step.
 From forall x_15: R_15(x_15) -> S_15(x_15) we can infer R_15(a_15) -> S_15(a_15) via universal instantiation. From s -> R_15(a_15), R_15(a_15) -> S_15(a_15) we can infer s -> S_15(a_15) via transitivity. From S_15(a_15) -> t_4, t_4 -> r_4 we can infer S_15(a_15) -> r_4 via transitivity. Finally, from s -> S_15(a_15), S_15(a_15) -> r_4 we can infer s -> r_4 via transitivity. Therefore, the answer is yes.