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What and Who
Title:Improvements in online bin packing
Speaker:Sandy Heydrich
coming from:Max-Planck-Institut f├╝r Informatik - D1
Speakers Bio:
Event Type:AG1 Mittagsseminar (own work)
Visibility:D1, D2, D3, D4, D5, RG1, SWS, MMCI
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Level:AG Audience
Language:English
Date, Time and Location
Date:Tuesday, 2 February 2016
Time:13:00
Duration:30 Minutes
Location:Saarbr├╝cken
Building:E1 4
Room:024
Abstract
In the online bin packing problem, items of sizes in (0,1] arrive online to be packed into bins of size 1. The goal is to minimize the number of used bins. In this paper, we present an online bin packing algorithm with asymptotic competitive ratio of 1.5817, which constitutes the first improvement over the algorithm Harmonic++ in fifteen years. This algorithm achieved a competitive ratio of 1.58889 and is one instance of the SuperHarmonic framework; a lower bound of Ramanan et al. shows that within this framework, no competitive ratio below 1.58333 can be achieved.

We make two crucial changes to that framework. First, some of the decisions of the algorithm will depend on exact sizes of items, instead of their rough sizes (called types), as done in SuperHarmonic. Furthermore, SuperHarmonic assigns items colors to control the packing process. In our framework, we postpone the coloring decision in order to be able to bound the number of bins where the optimal solution performs significantly better than our algorithm.

Finally, the analysis of our algorithm requires an additional step of marking items, which results in additional constraints in the linear program that describes the competitive ratio of the algorithm. We then solve this LP with the ellipsoid method, making use of a separation oracle.

In addition, we give a lower bound of 1.5766 for algorithms in our framework. This shows that fundamentally different ideas will be required to make further improvements.

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Name(s):Sandy Heydrich
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Created by:Sandy Heydrich, 01/20/2016 08:27 AMLast modified by:Uwe Brahm/MPII/DE, 11/24/2016 04:13 PM
  • Sandy Heydrich, 01/20/2016 08:27 AM -- Created document.