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: t -> s_2. s. t. q -> ~s.
s_2 can be inferred via the modus ponens rule. ~q can be inferred via the modus tollens rule. s and t can be inferred via the conjunction rule. t and s can be inferred via the conjunction rule.