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: r or ~q_7. q_4 or q_7. r <-> q_4.
q_7 -> r can be inferred via the rewriting rule. r -> q_4 can be inferred via the biconditional elimination rule. q_4 -> r can be inferred via the biconditional elimination rule.