- INSTANCE: Set of terminals in the plane, partition of into subsets .
- SOLUTION: Two-Level rectilinear Steiner Tree for in consisting of Steiner Trees for ( ) and a top-level tree connecting the trees
- COST FUNCTION: , where denotes the -length of the trees
- OBJECTIVE: Minimize.
*Approx.:*Approximable within , based on the PTAS for Rectilinear Steiner Tree in the plane [66].*Comment:*Admits a PTAS for the case when is fixed [66].

2015-04-27 Revision: 288 PDF version