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 <-> q_3. p -> q_3. q_3 or ~u_4. ~u_4.
u_4 -> q_3 can be inferred via the rewriting rule. u_4 -> q_3 can be inferred via the biconditional elimination rule. q_3 -> u_4 can be inferred via the biconditional elimination rule. ~q_3 can be inferred via the biconditional elimination rule.