Consider the following premises. t_2 -> t_1. ~r_1. t_1 -> r_1. Can we infer ~t_2 from them?
 From t_2 -> t_1, t_1 -> r_1 we can infer t_2 -> r_1. Finally, from t_2 -> r_1, ~r_1 we can infer ~t_2. Therefore, the answer is yes.