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: q_7. q <-> u_4. p_7 <-> u_4. p_7 -> ~q_7.
~p_7 can be inferred via the modus tollens rule. q -> u_4 can be inferred via the biconditional elimination rule. p_7 -> u_4 can be inferred via the biconditional elimination rule. u_4 -> q can be inferred via the biconditional elimination rule. u_4 -> p_7 can be inferred via the biconditional elimination rule.