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_2. q_3 <-> q_7. t_2 or ~q_7. t_2 -> u_2.
~t_2 can be inferred via the modus tollens rule. q_7 -> t_2 can be inferred via the rewriting rule. q_3 -> q_7 can be inferred via the biconditional elimination rule. q_7 -> q_3 can be inferred via the biconditional elimination rule.