We study the maximum weight matching problem in the semi-streaming model, and improve on the currently best one-pass algorithm due to Zelke (Proc.\ STACS~'08, pages 669--680) by devising a deterministic approach whose performance guarantee is $4.91 + \eps$. In addition, we study {\em preemptive} online algorithms, a sub-class of one-pass algorithms where we are only allowed to maintain a feasible matching in memory at any point in time. All known results prior to Zelke's belong to this sub-class. We provide a lower bound of $4.967$ on the competitive ratio of any such deterministic algorithm, and hence show that future improvements will have to store in memory a set of edges which is not necessarily a feasible matching. We conclude by presenting an empirical study, conducted in order to compare the practical performance of our approach to that of previously suggested algorithms.
@InProceedings{epstein_et_al:LIPIcs.STACS.2010.2476, author = {Epstein, Leah and Levin, Asaf and Mestre, Juli\'{a}n and Segev, Danny}, title = {{Improved Approximation Guarantees for Weighted Matching in the Semi-Streaming Model}}, booktitle = {27th International Symposium on Theoretical Aspects of Computer Science}, pages = {347--358}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-939897-16-3}, ISSN = {1868-8969}, year = {2010}, volume = {5}, editor = {Marion, Jean-Yves and Schwentick, Thomas}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2010.2476}, URN = {urn:nbn:de:0030-drops-24766}, doi = {10.4230/LIPIcs.STACS.2010.2476}, annote = {Keywords: Approximation guarantees, semi-streaming model, one-pass algorithm} }
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