Finding Pairwise Intersections of Rectangles in a Query Rectangle
We consider the following problem: Preprocess a set $\mathcal{S}$ of $n$ axis-parallel boxes in $\mathbb{R}^d$ so that given a query of an axis-parallel box in $\mathbb{R}^d$, the pairs of boxes of $\mathcal{S}$ whose intersection intersects the query box can be reported efficiently. For the case that $d=2$, we present a data structure of size $O(n\log n)$ supporting $O(\log n+k)$ query time, where $k$ is the size of the output. This improves the previously best known result by de Berg et al. which requires $O(\log n+ k\log n)$ query time using $O(n\log n)$ space. There has been no result known for this problem for higher dimensions, except that for $d=3$, the best known data structure supports $O(\sqrt{n}\log^2n+k\log^2n)$ query time using $O(n\sqrt {n}\log n)$ space. For a constant $d>2$, we present a data structure supporting $O(n^{1-δ}\log^{d-1} n + k \text{ polylog } n)$ query time for any constant $1/d\leqδ<1$. The size of the data structure is $O(n^{δd - 2δ+ 1}\log n)$.