A Better Approximation Ratio for the Vertex Cover Problem

We reduce the approximation factor for Vertex Cover to 2 − Θ( 1√ log n ) (instead of the previous 2 − Θ(log log n log n ), obtained by Bar-Yehuda and Even [2], and by Monien and Speckenmeyer [10]). The improvement of the vanishing factor comes as an application of the recent results of Arora, Rao, and Vazirani [1] that improved the approximation factor of the sparsest cut and balanced cut problems. In particular, we use the existence of two big and well-separated sets of nodes in the solution of the semidefinite relaxation for balanced cut, proven in [1]. We observe that a solution of the semidefinite relaxation for vertex cover, when strengthened with the triangle inequalities, can be transformed into a solution of a balanced cut problem, and therefore the existence of big well-separated sets in the sense of [1] translates into the existence of a big independent set.

• Type: Conference
• Year: 2005
• Where: ICALP
• Authors: George Karakostas
• Keywords: Approximation Factor, Balanced Cut, Balanced Cut Problem, ICALP 2005, Theoretical Computer Science