Makespan Minimization for Unrelated Parallel Machines with Maintenance Windows

It's a bit late, but last year during the Christmas break, Kaggle had a very interesting competition for the season. The story was that the toy list at Santa's workshop was long, and elves had to make all the toys, with some constraints on their productivity rating and rest intervals. This is an adaptation of the classic problem of minimizing makespan, though with additional constraints. A good leaderboard position could be achieved using offline methods since the entire list of toys was supplied in advance, but as usual I pursued online solutions for fun and speed. The problem they described can be reformulated as online makespan optimization for unrelated parallel machines with maintenance windows.