Independent Sets and Hitting Sets of Bicolored Rectangular Families

José A. Soto, Claudio Telha*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Bibliographical note

Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.

Keywords

  • Axis-parallel rectangles
  • Hitting set
  • Independent set
  • Jump number

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