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.
@InProceedings{fekete_et_al:LIPIcs.SoCG.2020.75, author = {Fekete, S\'{a}ndor P. and Keldenich, Phillip and Scheffer, Christian}, title = {{Covering Rectangles by Disks: The Video}}, booktitle = {36th International Symposium on Computational Geometry (SoCG 2020)}, pages = {75:1--75:4}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-143-6}, ISSN = {1868-8969}, year = {2020}, volume = {164}, editor = {Cabello, Sergio and Chen, Danny Z.}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.75}, URN = {urn:nbn:de:0030-drops-122337}, doi = {10.4230/LIPIcs.SoCG.2020.75}, annote = {Keywords: Disk covering, critical density, covering coefficient, tight worst-case bound, interval arithmetic, approximation} }
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