Ex i think when we have a set of possibilities or possible answers for a question, and the event is impossible or the question has no answer, because it has contradiction in itself, then the set of its possible answers would be null, and we can approve a theorem through Reductio ad absurdum.
But from my point of view, that set still is not representing "absolute nothingness" because it is assumed to be a set of answers for a special question, and still it is carries this information in its title, thus regardless of zero members it will provide, it is still differ from absolute nothingness.