A Better-Than-2 Approximation for Weighted Tree Augmentation

We present an approximation algorithm for Weighted Tree Augmentation with approximation factor 1+ln 2+ε < 1.7. This is the first algorithm beating the longstanding factor of 2, which can be achieved through many standard techniques. ∗This project received funding from Swiss National Science Foundation grant 200021 184622 and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 817750). ‡Department of Mathematics, ETH Zurich, Zurich, Switzerland. Email: vera.traub@ifor.math.ethz.ch. §Department of Mathematics, ETH Zurich, Zurich, Switzerland. Email: ricoz@ethz.ch. ar X iv :2 10 4. 07 11 4v 1 [ cs .D S] 1 4 A pr 2 02 1

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