A set is multi-ordered if it comes with strict weak orders , for some integer . A multi-interval in is a set of the form , where is an interval in with respect to . Range searching is the problem of reporting the set , for a given multi-interval . Range counting is the problem of reporting the integer , for a given multi-interval .
Our definition is more general than usual. The usual definition is recovered by setting and . In this case a multi-interval becomes an axis-aligned box, also called an orthogonal range. Our definition can be used also for non-orthogonal range searching. One such example is given by , , and .