- INSTANCE:
Graph
, the edge weights
, a polymatroid
.
- SOLUTION: A tree in such that , and spans base of .
- COST FUNCTION:
- OBJECTIVE: Minimize.
*Approx.:*Approximable within [24], [27], [32].*Hardness:*NP-hard to approximate within for every [61], [24].*Comment:*The problem contains the Group Steiner Tree Problem as a special case [24].

2015-04-27 Revision: 288 PDF version