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_4 <-> q_4. s_4 -> r_4. p -> s_4. q_4 or p.
p -> r_4 can be inferred via the transitivity rule. r_4 -> q_4 can be inferred via the biconditional elimination rule. q_4 -> r_4 can be inferred via the biconditional elimination rule.