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: u -> q_12. q_2 <-> q_12. ~q_2. t_3.
~q_2 and t_3 can be inferred via the conjunction rule. t_3 and ~q_2 can be inferred via the conjunction rule. q_2 -> q_12 can be inferred via the biconditional elimination rule. q_12 -> q_2 can be inferred via the biconditional elimination rule. ~q_12 can be inferred via the biconditional elimination rule.