O(log² k/log log k)-APPROXIMATION ALGORITHM FOR DIRECTED STEINER TREE: A TIGHT QUASI-POLYNOMIAL TIME ALGORITHM

In the directed Steiner tree (DST) problem, we are given an n-vertex directed edge-weighted graph, a root r, and a collection of k terminal nodes. Our goal is to find a minimum-cost subgraph that contains a directed path from r to every terminal. We present an O(log(2) k/ log log k)-approximation algorithm for DST that runs in quasi-polynomial time, i.e., in time npoly log(k). By assuming the projection game conjecture and NP not subset of boolean AND(0更多