- INSTANCE: Graph , node weights , penalties
- SOLUTION: A tree in
- COST FUNCTION:
- OBJECTIVE: Minimize
*Approx.:*Approximable within approximation ratio [77]*Hardness:*NP-hard to approximate within for some [77] For the online version of the problem, there exists an algorithm with polylogarithmic competitive ratio [59].

2015-04-27 Revision: 288 PDF version