# Real-world scenario for a theoretical problem on trees

Suppose one has a tree with each node weighted with a tuple (say, some fixed $$2$$ dimensions, for now) of integers. Now we query the tree with two vertices $$x$$ and $$y$$ and a range $$[a,b]\times [c,d]$$, and the query should return the number of nodes in the (unique) path from $$x$$ to $$y$$ such that their tuples fall within this rectangle $$[a,b]\times [c,d]$$. What would be a possible real-world scenario that would result in such a model?

For the 1d-case, one could use, say, Homory-Hu tree of minimum cuts to motivate such a problem. I am not sure how to motivate this theoretical question with a real-life problem, that is the question.

Suppose the path $$x\sim y$$ has vertices $$u_1,u_2,\ldots,u_m$$ with attached tuples (respectively) $$(-1,2),(3,4),\ldots,(13,-17).$$ Then if we query with $$x,y$$ and a rectangle $$[-2,2]\times[2,3]$$, then the first node, $$u_1$$ (among possibly others) would be counted, since its tuple $$(-1,2) \in [-2,2]\times [2,3].$$

• You can ask this question for a lot of different theoretical problems. What makes this particular question special? – Yuval Filmus Apr 22 '19 at 13:47
• What are you going to use this real-world scenario for? Why do you need to motivate your theoretical model? – Discrete lizard Apr 22 '19 at 14:31