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On guillotine separable packings for the two-dimensional geometric knapsack problem

Khan, A and Maiti, A and Sharma, A and Wiese, A (2021) On guillotine separable packings for the two-dimensional geometric knapsack problem. In: 37th International Symposium on Computational Geometry, SoCG 2021, 7-11, June 2021, Virtual, Buffalo.

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Official URL: https://doi.org/10.4230/LIPIcs.SoCG.2021.48


In two-dimensional geometric knapsack problem, we are given a set of n axis-aligned rectangular items and an axis-aligned square-shaped knapsack. Each item has integral width, integral height and an associated integral profit. The goal is to find a (non-overlapping axis-aligned) packing of a maximum profit subset of rectangles into the knapsack. A well-studied and frequently used constraint in practice is to allow only packings that are guillotine separable, i.e., every rectangle in the packing can be obtained by recursively applying a sequence of edge-to-edge axis-parallel cuts that do not intersect any item of the solution. In this paper we study approximation algorithms for the geometric knapsack problem under guillotine cut constraints. We present polynomial time (1 + ε)-approximation algorithms for the cases with and without allowing rotations by 90 degrees, assuming that all input numeric data are polynomially bounded in n. In comparison, the best-known approximation factor for this setting is 3 + ε Jansen-Zhang, SODA 2004, even in the cardinality case where all items have the same profit. Our main technical contribution is a structural lemma which shows that any guillotine packing can be converted into another structured guillotine packing with almost the same profit. In this packing, each item is completely contained in one of a constant number of boxes and L-shaped regions, inside which the items are placed by a simple greedy routine. In particular, we provide a clean sufficient condition when such a packing obeys the guillotine cut constraints which might be useful for other settings where these constraints are imposed. © Arindam Khan, Arnab Maiti, Amatya Sharma, and Andreas Wiese; licensed under Creative Commons License CC-BY 4.0 37th International Symposium on Computational Geometry (SoCG 2021).

Item Type: Conference Paper
Publication: Leibniz International Proceedings in Informatics, LIPIcs
Publisher: Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
Additional Information: The copyright for this article belongs to Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
Keywords: Combinatorial optimization; Computational geometry; Polynomial approximation; Profitability, Approximation factor; Cardinalities; Knapsack problems; Maximum profits; Numeric data; Parallel cuts; Polynomial-time; Technical contribution, Approximation algorithms
Department/Centre: Division of Electrical Sciences > Computer Science & Automation
Date Deposited: 04 Aug 2021 12:11
Last Modified: 04 Aug 2021 12:11
URI: http://eprints.iisc.ac.in/id/eprint/69012

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