A bicolored rectangular family BRF is the collection of all axis-parallel rectangles formed by selecting a bottom-left corner from a finite set of points A and an upper-right corner from a finite set of points B. We devise a combinatorial algorithm to compute the maximum independent set and the minimum hitting set of a BRF that runs in O(n2.5logn)-time, where n= | A| + | B|. This result significantly reduces the gap between the Ω (n7) -time algorithm by Benczúr (Discrete Appl Math 129 (2–3):233–262, 2003) for the more general problem of finding directed covers of pairs of sets, and the O(n2) -time algorithms of Franzblau and Kleitman (Inf Control 63(3):164–189, 1984) and Knuth (ACM J Exp Algorithm 1:1, 1996) for BRFs where the points of A lie on an anti-diagonal line. Furthermore, when the bicolored rectangular family is weighted, we show that the problem of finding the maximum weight of an independent set is NP-hard, and provide efficient algorithms to solve it on important subclasses.
CITATION STYLE
Soto, J. A., & Telha, C. (2021). Independent Sets and Hitting Sets of Bicolored Rectangular Families. Algorithmica, 83(6), 1918–1952. https://doi.org/10.1007/s00453-021-00810-1
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