Polynomial-Time Separation of Simple Comb Inequalities

  • Adam N. Letchford
  • Andrea Lodi
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2337)


The comb inequalities are a well-known class of facet-inducing inequalities for the Traveling Salesman Problem, defined in terms of certain vertex sets called the handle and the teeth. We say that a comb inequality is simple if the following holds for each tooth: either the intersection of the tooth with the handle has cardinality one, or the part of the tooth outside the handle has cardinality one, or both. The simple comb inequalities generalize the classical 2-matching inequalities of Edmonds, and also the so-called Chvátal comb inequalities.

In 1982, Padberg and Rao [29] gave a polynomial-time algorithm for separating the 2-matching inequalities — i.e., for testing if a given fractional solution to an LP relaxation violates a 2-matching inequality. We extend this significantly by giving a polynomial-time algorithm for separating the simple comb inequalities. The key is a result due to Caprara and Fischetti.


Travel Salesman Problem Valid Inequality Separation Algorithm Fractional Point Degree Equation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Adam N. Letchford
    • 1
  • Andrea Lodi
    • 2
  1. 1.Department of Management ScienceLancaster UniversityLancasterEngland
  2. 2.D.E.I.S.University of BolognaBolognaItaly

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