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. ~p_13. p_13 <-> u_2. p -> t. u_2 <-> p.
t <-> p can be inferred via the biconditional introduction rule. p <-> t can be inferred via the biconditional introduction rule. p_13 -> u_2 can be inferred via the biconditional elimination rule. u_2 -> p can be inferred via the biconditional elimination rule. u_2 -> p_13 can be inferred via the biconditional elimination rule. p -> u_2 can be inferred via the biconditional elimination rule. ~u_2 can be inferred via the biconditional elimination rule.