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: t_1 <-> u. t_1. q_12. w_2 -> ~q_12.
~w_2 can be inferred via the modus tollens rule. t_1 and q_12 can be inferred via the conjunction rule. q_12 and t_1 can be inferred via the conjunction rule. t_1 -> u can be inferred via the biconditional elimination rule. u -> t_1 can be inferred via the biconditional elimination rule.