Consider the following premises. r_1 <-> t_3. q_1. ~t_3. r_1 <-> r. Can we infer r from them?
 From r_1 <-> t_3, ~t_3 we can infer ~r_1. Finally, from r_1 <-> r, ~r_1 we can infer ~r, which contradicts r. Therefore, the answer is no.