When your three cases run into someone else’s two you have six, and it can even get much worse than that. Or an object running into itself and getting nine case

When your three cases run into someone else’s two you have six, and it can even get much worse than that. Or an object running into itself and getting nine cases. Intervals are nice for representing acceptable ranges. Half intervals mean greater/less than. If you stick infinities on the ends, everything likely works. You then expose methods or functions for all your operations. From the outside, you don’t have to care if it’s a half interval or not (unless that is what you’re particularly checking). On the inside you don’t really, either. If you’re messing with intervals in a business setting, it’s worth considering if you need multi intervals, non continuous regions. These are all great for handling uncertainty. Like if you add two weights that have +/- values, you can have the sum have those and be correct. The math is all well defined and rather easy. Wikipedia has good pages on it.