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We present new results for LambdaCC and MotifCC, two recently introduced variants of the well-studied correlation clustering problem. Both variants are motivated by applications to network analysis and community detection, and have non-trivial approximation algorithms. We first show that the standard linear programming relaxation of LambdaCC has a Theta(log n) integrality gap for a certain choice of the parameter lambda. This sheds light on previous challenges encountered in obtaining parameter-independent approximation results for LambdaCC. We generalize a previous constant-factor algorithm to provide the best results, from the LP-rounding approach, for an extended range of lambda. MotifCC generalizes correlation clustering to the hypergraph setting. In the case of hyperedges of degree 3 with weights satisfying probability constraints, we improve the best approximation factor from 9 to 8. We show that in general our algorithm gives a 4(k-1) approximation when hyperedges have maximum degree k and probability weights. We additionally present approximation results for LambdaCC and MotifCC where we restrict to forming only two clusters.
@InProceedings{gleich_et_al:LIPIcs.ISAAC.2018.44,
author = {Gleich, David F. and Veldt, Nate and Wirth, Anthony},
title = {{Correlation Clustering Generalized}},
booktitle = {29th International Symposium on Algorithms and Computation (ISAAC 2018)},
pages = {44:1--44:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-094-1},
ISSN = {1868-8969},
year = {2018},
volume = {123},
editor = {Hsu, Wen-Lian and Lee, Der-Tsai and Liao, Chung-Shou},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2018.44},
URN = {urn:nbn:de:0030-drops-99925},
doi = {10.4230/LIPIcs.ISAAC.2018.44},
annote = {Keywords: Correlation Clustering, Approximation Algorithms}
}