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DTSTART:20240310T070000
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DTSTART;TZID=America/Toronto:20240607T153000
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URL:/combinatorics-and-optimization/events/tutte-colloq
 uium-euiwoong-lee
SUMMARY:Tutte Colloquium - Euiwoong Lee
CLASS:PUBLIC
DESCRIPTION:Summary \n\nTITLE: Recent Progresses on Correlation Clustering
 \n\nSPEAKER:\n Euiwoong Lee\n\nAFFILIATION:\n University of Michigan\n\nLO
 CATION:\n MC 5501\n\nABSTRACT: Correlation Clustering is one of the most 
 well-studied\ngraph clustering problems. The input is a complete graph whe
 re each\nedge is labeled either \"+\" or \"-\"\, and the goal is to partit
 ion the\nvertex set into (an arbitrary number of) clusters to minimize (th
 e\nnumber of + edges between different clusters) + (the number of - edges\
 nwithin the same cluster). Until recently\, the best polynomial-time\nappr
 oximation ratio was 2.06\, nearly matching the integrality gap of 2\nfor t
 he standard LP relaxation. Since 2022\, we have bypassed this\nbarrier and
  progressively improved the approximation ratio\, with the\ncurrent ratio 
 being 1.44. Based on a new relaxation inspired by the\nSherali-Adams hiera
 rchy\, the algorithm introduces and combines several\ntools considered in 
 different contexts\, including \"local to global\ncorrelation rounding\" a
 nd \"combinatorial preclusering\". In this talk\,\nI will describe the cur
 rent algorithm as well as how it has been\ninspired by various viewpoints.
  Joint work with Nairen Cao\, Vincent\nCohen-Addad\, Shi Li\, Alantha Newm
 an\, and Lukas Vogl.\n 
DTSTAMP:20250706T090804Z
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