A New Approximation Algorithm for the Minimum 2-Edge-Connected Spanning Subgraph Problem

We present a new approximation algorithm for the minimum 2-edge-connected spanning subgraph problem. Its approximation ratio is $\frac{4}{3}$, which matches the current best ratio. The approximation ratio of the algorithm is $\frac{6}{5}$ on subcubic graphs, which is an improvement upon the previous best ratio of $\frac{5}{4}$. The algorithm is a novel extension of the primal-dual schema, which consists of two distinct phases. Both the algorithm and the analysis are much simpler than those of the previous approaches.