Breaching the 2-approximation barrier for the forest augmentation problem

@article{Grandoni2021BreachingT2,
  title={Breaching the 2-approximation barrier for the forest augmentation problem},
  author={Fabrizio Grandoni and Afrouz Jabal Ameli and Vera Traub},
  journal={Proceedings of the 54th Annual ACM SIGACT Symposium on Theory of Computing},
  year={2021}
}
The basic goal of survivable network design is to build cheap networks that guarantee the connectivity of certain pairs of nodes despite the failure of a few edges or nodes. A celebrated result by Jain [Combinatorica'01] provides a 2-approximation for a wide class of these problems. However nothing better is known even for very basic special cases, raising the natural question whether any improved approximation factor is possible at all. In this paper we address one of the most basic problems… 
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