Proposed by Michael Parish: a flight has been cancelled, and its passengers need to be re-booked onto other flights. The rebooking decision has to take into account each passenger’s frequent-flyer status, accumulated miles, and the seat availability on candidate replacement flights.
This one turned out to have real staying power — it kept attracting new solutions (including an optimization-based approach and a declarative rule-solver version) for years after it was first posted.
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