Consider the following premises. p_13 <-> q_1. ~t_3. p_13 <-> t_3. Can we infer ~q_1 or r_1 from them? If possible, name the inference rules being used at each step.
 From p_13 <-> t_3, ~t_3 we can infer ~p_13 via biconditional elimination. From p_13 <-> q_1, ~p_13 we can infer ~q_1 via biconditional elimination. Finally, from ~q_1 we can infer ~q_1 or r_1 via addition. Therefore, the answer is yes.