Combining two worlds: Parameterised approximation for vertex cover

Abstract

We explore opportunities for parameterising constant factor approximation algorithms for vertex cover. We provide a simple algorithm that works on any approximation ratio of the form 2l+1/l+1 and has complexity that outperforms an algorithm by Bourgeois et al. derived from a sophisticated exact parameterised algorithm. In particular, for l=1 (factor 1.5 approximation) our algorithm runs in time O*(1.09+). Additionally, we present an improved polynomial-time approximation algorithm for graphs of average degree four. © 2010 Springer-Verlag.