This morning I read Wendy Kan’s interesting post on Creating Santa’s Stolen Sleigh. I hadn’t really thought too much about the process of constructing an optimisation competition, but Wendy gave some interesting insights on the considerations involved in designing a competition which was both fun and challenging but still computationally feasible without military grade hardware.
This seems like an opportune time to jot down some of my personal notes and also take a look at the results. I know that this sort of discussion is normally the prerogative of the winners and I trust that my ramblings won’t be viewed as presumptuous.
Santa’s Stolen Sleigh closed on 8 January 2016. At the top of the leaderboard:
Well done, what a phenomenal effort!
Problem Summary
The problem could be summarised as follows: 100 000 Christmas gifts have to be delivered from the North Pole to various locations across the Earth while minimising the Weighted Reindeer Weariness, a metric depending on weight carried and distance travelled. Distances were to be calculated using the Haversine formula which takes into account the curvature of the Earth’s quasi-spherical surface. Each gift had a weight between 1 and 50 (units unspecified). In addition the sleigh itself had a weight of 10 (same unspecified and obviously rather magical units) and a weight capacity of 1000.
… when the sleigh weight was too small, there’s no incentive to merge any trips.Wendy Kan
The problem could be decomposed into two parts:
- partition the gifts into trips, where the total weight of gifts to be delivered on any particular trip must satisfy the weight constraint of the sleigh; and
- choose the order in which the gifts should be delivered on each trip.
A solution would jointly solve both parts in such a way as to minimise Weighted Reindeer Weariness. It’s a variation of the Travelling Salesman Problem. …read more
Source:: r-bloggers.com