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: u_4 -> p_14. r_2. ~r_3. p_28 <-> r_3. p_14 -> p_28.
r_2 and ~r_3 can be inferred via the conjunction rule. ~r_3 and r_2 can be inferred via the conjunction rule. p_28 -> r_3 can be inferred via the biconditional elimination rule. r_3 -> p_28 can be inferred via the biconditional elimination rule. ~p_28 can be inferred via the biconditional elimination rule.