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_1 -> p. u_4 -> q_1. p_8 <-> u_4.
u_4 -> p can be inferred via the transitivity rule. p_8 -> u_4 can be inferred via the biconditional elimination rule. u_4 -> p_8 can be inferred via the biconditional elimination rule.