What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: q_1 -> s_2. q_1 or t_2. ~r_4. t_2 -> s_2. p_28 <-> r_4. p_5 -> p_28.
s_2 can be inferred via the disjunction elimination rule. p_28 -> r_4 can be inferred via the biconditional elimination rule. r_4 -> p_28 can be inferred via the biconditional elimination rule. ~p_28 can be inferred via the biconditional elimination rule.