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: p_13 <-> t. q_4 -> p_13. q_4 or ~q_2.
q_2 -> q_4 can be inferred via the rewriting rule. p_13 -> t can be inferred via the biconditional elimination rule. t -> p_13 can be inferred via the biconditional elimination rule.