### Abstract

We study the fundamental classification problems 0-EXTENSION and METRIC LABELING. 0-EXTENSION is closely related to partitioning problems in graph theory and to Lipschitz extensions in Banach spaces; its generalization METRIC LABELING is motivated by applications in computer vision. Researchers had proposed using earthmover metrics to get polynomial time-solvable relaxations for these problems. A conjecture that has attracted much attention recently is that the integrality ratio for these relaxations is constant. We prove 1. that the integrality ratio of the earthmover relaxation for METRIC LABELING is Ω(log n) (which is asymptotically tight), k being the number of labels, whereas the best previous lower bound on the integrality ratio was only constant; 2. that the integrality ratio of the earthmover relaxation for 0-ExTENSiON is Ω(√logk), k being the number of terminals (it was known to be O((log k) / log log k)), whereas the best previous lower bound was only constant; 3. that for no ε > 0 is there a polynomial-time O((log n)^{1/4-ε})-approximation algorithm for 0-EXTENSION, n being the number of vertices, unless NP⊆DTIME(n^{poly(log n)}), whereas the strongest in-approximability result known before was only MAX SNP-hardness; and 4. that there is a polynomial-time approximation algorithm for 0-EXTENSION with performance ratio O(√diam((d)) where diam(d) is the ratio of the largest to smallest nonzero distances in the terminal metric.

Original language | English (US) |
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Title of host publication | STOC'06 |

Subtitle of host publication | Proceedings of the 38th Annual ACM Symposium on Theory of Computing |

Publisher | Association for Computing Machinery |

Pages | 547-556 |

Number of pages | 10 |

ISBN (Print) | 1595931341, 9781595931344 |

DOIs | |

State | Published - Jan 1 2006 |

Event | 38th Annual ACM Symposium on Theory of Computing, STOC'06 - Seattle, WA, United States Duration: May 21 2006 → May 23 2006 |

### Publication series

Name | Proceedings of the Annual ACM Symposium on Theory of Computing |
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Volume | 2006 |

ISSN (Print) | 0737-8017 |

### Other

Other | 38th Annual ACM Symposium on Theory of Computing, STOC'06 |
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Country | United States |

City | Seattle, WA |

Period | 5/21/06 → 5/23/06 |

### Keywords

- Algorithms
- Theory

### ASJC Scopus subject areas

- Software

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## Cite this

*STOC'06: Proceedings of the 38th Annual ACM Symposium on Theory of Computing*(pp. 547-556). (Proceedings of the Annual ACM Symposium on Theory of Computing; Vol. 2006). Association for Computing Machinery. https://doi.org/10.1145/1132516.1132595