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: s <-> u. ~u_3. s <-> u_3. p_1.
~u_3 and p_1 can be inferred via the conjunction rule. p_1 and ~u_3 can be inferred via the conjunction rule. s -> u can be inferred via the biconditional elimination rule. s -> u_3 can be inferred via the biconditional elimination rule. u -> s can be inferred via the biconditional elimination rule. u_3 -> s can be inferred via the biconditional elimination rule. ~s can be inferred via the biconditional elimination rule.