The traveling salesman problem on cubic and subcubic graphs

@article{Boyd2014TheTS,
  title={The traveling salesman problem on cubic and subcubic graphs},
  author={Sylvia C. Boyd and Ren{\'e} Sitters and Suzanne van der Ster and Leen Stougie},
  journal={Mathematical Programming},
  year={2014},
  volume={144},
  pages={227-245}
}
We study the traveling salesman problem (TSP) on the metric completion of cubic and subcubic graphs, which is known to be NP-hard. The problem is of interest because of its relation to the famous 4/3-conjecture for metric TSP, which says that the integrality gap, i.e., the worst case ratio between the optimal value of a TSP instance and that of its linear programming relaxation (the subtour elimination relaxation), is 4/3. We present the first algorithm for cubic graphs with approximation ratio… 

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