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: t -> p_11. p_11 -> t. u_3 -> r. p_11 -> u_3.
t -> u_3 can be inferred via the transitivity rule. p_11 -> r can be inferred via the transitivity rule. t <-> p_11 can be inferred via the biconditional introduction rule. p_11 <-> t can be inferred via the biconditional introduction rule.