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_3. p_3 <-> u_2. u_2 <-> u.
p_3 -> u_2 can be inferred via the biconditional elimination rule. u_2 -> u can be inferred via the biconditional elimination rule. u_2 -> p_3 can be inferred via the biconditional elimination rule. u -> u_2 can be inferred via the biconditional elimination rule. ~u_2 can be inferred via the biconditional elimination rule.