Directed Steiner Tree Packing Problem
摘要
In the two former sections, we introduce the complexity for the decision versions of IDSTP and ADSTP on general digraphs, symmetric digraphs and Eulerian digraphs. The hardness of approximation of ADSTP and IDSTP and their generalizations are also mentioned in Sect. 2.1. In the last section, Sect. 2.3, we introduce three related topics: directed tree connectivity, independent directed Steiner trees and independent branchings, and arc-disjoint in- and out-branchings rooted at the same vertex.