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: w -> s. w or q. ~s. t_1 <-> q.
~w can be inferred via the modus tollens rule. t_1 -> q can be inferred via the biconditional elimination rule. q -> t_1 can be inferred via the biconditional elimination rule.