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: q -> p_4. t or ~q_12. s_4 -> q_12. p_4 <-> s_4.
q_12 -> t can be inferred via the rewriting rule. p_4 -> s_4 can be inferred via the biconditional elimination rule. s_4 -> p_4 can be inferred via the biconditional elimination rule.