We have illustrated the traditional CPM algorithm for finding the project length and the critical path. An alternative method is sometimes used. It sets up a Solver model for finding a feasible solution to a set of constraints, and there is no objective to maximize or minimize. Let dj be the duration of activity j, and let tj be the start time of activity j. Let the tj’s be the changing cells in the Solver model. There is a constraint for each arc in the AON network. Specifically, if there is an arc from activity i to activity j, then there is a constraint tj  ti  di. This states that activity j cannot start until its predecessor, activity i, finishes. Develop this Solver model for the LAN project, making sure that there is no target cell in the Solver dialog box.

(Just delete whatever is in the Target Cell box.) Then run Solver to find the project completion time. Can you tell from the solution which activities are critical?