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_15. u -> q. q <-> w. w -> q_15.
~w can be inferred via the modus tollens rule. q -> w can be inferred via the biconditional elimination rule. w -> q can be inferred via the biconditional elimination rule.