What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? q_2 <-> u_4. p <-> t_2. t_2 or ~q_2. ~p.
q_2 -> t_2. q_2 -> u_4. p -> t_2. u_4 -> q_2. t_2 -> p. ~t_2.