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# Covering Rectangles by Disks: The Video (Media Exposition)

## File

LIPIcs.SoCG.2020.75.pdf
• Filesize: 0.83 MB
• 4 pages

## Acknowledgements

We thank Sebastian Morr, Utkarsh Gupta and Sahil Shah for joint related work.

## Cite As

Sándor P. Fekete, Phillip Keldenich, and Christian Scheffer. Covering Rectangles by Disks: The Video (Media Exposition). In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 75:1-75:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)
https://doi.org/10.4230/LIPIcs.SoCG.2020.75

## Abstract

In this video, we motivate and visualize a fundamental result for covering a rectangle by a set of non-uniform circles: For any λ ≥ 1, the critical covering area A^*(λ) is the minimum value for which any set of disks with total area at least A^*(λ) can cover a rectangle of dimensions λ× 1. We show that there is a threshold value λ₂ = √(√7/2 - 1/4) ≈ 1.035797…, such that for λ < λ₂ the critical covering area A^*(λ) is A^*(λ) = 3π(λ²/16 + 5/32 + 9/256λ²), and for λ ≥ λ₂, the critical area is A^*(λ) = π(λ²+2)/4; these values are tight. For the special case λ=1, i.e., for covering a unit square, the critical covering area is 195π/256 ≈ 2.39301…. We describe the structure of the proof, and show animations of some of the main components.

## Subject Classification

##### ACM Subject Classification
• Theory of computation → Packing and covering problems
• Theory of computation → Computational geometry
##### Keywords
• Disk covering
• critical density
• covering coefficient
• tight worst-case bound
• interval arithmetic
• approximation

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## References

1. Sándor P. Fekete, Utkarsh Gupta, Phillip Keldenich, Christian Scheffer, and Sahil Shah. Worst-Case Optimal Covering of Rectangles by Disks. In Proceedings 36th International Symposium on Computational Geometry (SoCG 2020), pages 42:1-42:19, 2020. URL: https://doi.org/10.4230/LIPIcs.SoCG.2019.35.
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