A Deterministic Distributed $2$-Approximation for Weighted Vertex Cover in $O(\log n\logΔ/ \log^2\logΔ)$ Rounds

Abstract: We present a deterministic distributed $2$-approximation algorithm for the Minimum Weight Vertex Cover problem in the CONGEST model whose round complexity is $O(\log n \log \Delta / \log^2 \log \Delta)$. This improves over the currently best known deterministic 2-approximation implied by [KVY94]. Our solution generalizes the $(2+\epsilon)$-approximation algorithm of [BCS17], improving the dependency on $\epsilon^{-1}$ from linear to logarithmic. In addition, for every $\epsilon=(\log \Delta)^{-c}$, where $c\geq 1$ is a constant, our algorithm computes a $(2+\epsilon)$-approximation in $O(\log \Delta / \log \log \Delta)$~rounds (which is asymptotically optimal).