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: p -> u. u <-> t_2. t_2 <-> u_2. ~u_2.
u -> t_2 can be inferred via the biconditional elimination rule. t_2 -> u_2 can be inferred via the biconditional elimination rule. t_2 -> u can be inferred via the biconditional elimination rule. u_2 -> t_2 can be inferred via the biconditional elimination rule. ~t_2 can be inferred via the biconditional elimination rule.