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 -> t. q. s_2 or r_1.
~s_2 can be inferred via the modus tollens rule. ~t and q can be inferred via the conjunction rule. q and ~t can be inferred via the conjunction rule.