The New York Times has a nice article on what goes into scheduling the (tennis) US Open. You would think that most of the scheduling is done once the brackets are determined, but that is not the case. While the brackets determine who plays on each day, the assignment of matches to courts and to times of the day is done live, and depends on the outcomes of the matches. Venus Williams wins, and her match goes into a big court at a time best for TV. Venus loses, and her conqueror may be exiled to an outer court at 11AM.
There are lots of things that go into the schedule:
The task is to balance the often conflicting desires of players (who submit match-time preferences before the tournament), coaches (who often have more than one pupil and prefer they play at different times), broadcasters (including three in the United States and a litany of others around the world, each hoping to boost ratings with well-timed slots for particular players) and ticket holders (some holding passes for daytime matches, others with tickets to the prime-time show, all wanting compelling tennis spread evenly throughout their stay).
This is, of course, a great opportunity for operations research: our models are really good at doing this sort of scheduling. The hard part is doing the balancing: what should the objective be?
It appears that the system they have in place primarily tracks things as people hand-schedule:
To demonstrate, Curley and Crossland moved Friday’s matches around, cutting and pasting from one court to another, from one time to another. A matchup, outlined in blue for men and pink for women, would turn red if the computer recognized a problem.
In one case, a player had a doubles match before her singles match — a no-no. In others, the computer flagged too little rest for players. Several noted that coaches had players playing simultaneously.
Clicking on a command called “pairs” showed the two matches whose winners would meet in the next round. Ideally, the matches take place at the same time, giving each winning player the same amount of rest leading into the next match.
This is not the sort of interface or description you would expect if the system was optimizing the schedule.
I have seen a very nice paper on tennis umpire scheduling which talks about scheduling the umpires for the US Open but there the constraints and requirements are a lot clearer. It would be quite challenging to put together a system for scheduling the matches that would allow for the sort of tradeoffs the hand-scheduling provides. But I would love to try to do so!
Very nice post Mike and a very interesting problem. Whenever I have thought about tennis, it always appears NOT to be a scheduling problem (you make the draw and who plays who is determined from that).
But the problem you have described is not only “fuzzy” (what is the objective function?), but also dynamic (you have to schedule after each match/round).
Thanks
It gets a little more confusing, if a person is playing in more than one event (singles and doubles). Then, not only should his schedule meet all of the requirements mentioned before, but also his singles match must not conflict with his doubles match either.