Two Approximation Algorithms for ATSP with Strengthened Triangle Inequality

  • Authors:
  • Łukasz Kowalik;Marcin Mucha

  • Affiliations:
  • Institute of Informatics, University of Warsaw, Poland;Institute of Informatics, University of Warsaw, Poland

  • Venue:
  • WADS '09 Proceedings of the 11th International Symposium on Algorithms and Data Structures
  • Year:
  • 2009

Quantified Score

Hi-index 0.01

Visualization

Abstract

In this paper, we study the asymmetric traveling salesman problem (ATSP) with strengthened triangle inequality, i.e. for some $\gamma\in [\frac{1}{2},1)$ the edge weights satisfy w (u ,v ) ≤ γ (w (u ,x ) + w (x ,v )) for all distinct vertices u ,v ,x . We present two approximation algorithms for this problem. The first one is very simple and has approximation ratio $\frac{1}{2(1-\gamma)}$, which is better than all previous results for all $\gamma \in (\frac{1}{2},1)$. The second algorithm is more involved but it also gives a much better approximation ratio: $\frac{2-\gamma}{3(1-\gamma)}+O(\frac{1}{n})$ when γ γ 0 , and $\frac{1}{2}(1+\gamma)^2 + \epsilon$ for any ε 0 when γ ≤ γ 0 , where γ 0 ≅ 0.7003.