The Lost Group Chart and Related Problems

In the basement of the house is a fuse box, where the main electricity supply is distributed over ten separately fused groups. Each fuse protects a number of the—more than fifty— power outlets in and around the house. For reasons that need not concern us here, the mapping from outlet to fuse group is rather haphazard. Unfortunately, the previous owner had lost the group chart that lists for every outlet the fuse group to which it belongs. Thus, I encountered the problem of reconstructing the lost group chart.