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: ~s. ~p_7. s or q_13. p_7 <-> t.
q_13 can be inferred via the disjunctive syllogism rule. ~s and ~p_7 can be inferred via the conjunction rule. ~p_7 and ~s can be inferred via the conjunction rule. p_7 -> t can be inferred via the biconditional elimination rule. t -> p_7 can be inferred via the biconditional elimination rule. ~t can be inferred via the biconditional elimination rule.