Consider the following premises. p -> t_4. p_15 or p. r_1 -> ~t_4. p_15 -> t_4. ~r_1 -> s_3. Can we infer ~s_3 from them?
 From p_15 -> t_4, p -> t_4, p_15 or p we can infer t_4. From r_1 -> ~t_4, t_4 we can infer ~r_1. Finally, from ~r_1 -> s_3, ~r_1 we can infer s_3, which contradicts ~s_3. Therefore, the answer is no.