As mentioned before, only optimal solution procedures for the resource investment problem have been presented so far making use of rather small test sets. Hence, we decided to adapt well established instances for the resource constrained project scheduling problem for our purposes. The project scheduling problem library PSPLIB (see page 51) provides a collection of systematically generated instances. We used the 480 instances with
*n* = 30
non-dummy activities and*K*= 4
resources. The resource limits of these instances have no meaning in our context, so we simply ignored them. The ProGen instances have different network complexities
*NC* ∈ 1.5, 1.8, 2.1
and different resource factors
*RF* ∈ 0.25, 0.5, 0.75, 1.0.