I can use the Chu-Liu/Edmonds algorithm to get the minimum cost arborescence of a directed weighted graph. I want to apply this for a pre-specified subset of k vertices. (I know exactly which k vertices must be included in the the tree).
What are the steps required to apply the Chu-Liu/Edmonds algorithm?
Similar to Construct a minimum spanning tree covering a specific subset of the vertices, but for directed graphs / minimum cost arborescence (vs. undirected graphs / minimum spanning tree).