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CORR

2011

Springer

2011

Springer

We study the lift-and-project procedures of Lov´asz-Schrijver and Sherali-Adams applied to the standard linear programming relaxation of the traveling salesperson problem with triangle inequality. For the asymmetric TSP tour problem, Charikar, Goemans, and Karloﬀ (FOCS 2004) proved that the integrality gap of the standard relaxation is at least 2. We prove that after one round of the Lov´asz-Schrijver or Sherali-Adams procedures, the integrality gap of the asymmetric TSP tour problem is at least 3/2, with a small caveat on which version of the standard relaxation is used. For the symmetric TSP tour problem, the integrality gap of the standard relaxation is known to be at least 4/3, and Cheung (SIOPT 2005) proved that it remains at least 4/3 after o(n) rounds of the Lov´asz-Schrijver procedure, where n is the number of nodes. For the symmetric TSP path problem, the integrality gap of the standard relaxation is known to be at least 3/2, and we prove that it remains at least 3/2 aft...

Related Content

Added |
19 Aug 2011 |

Updated |
19 Aug 2011 |

Type |
Journal |

Year |
2011 |

Where |
CORR |

Authors |
Thomas Watson |

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