Instance Created:  July 29, 2001
Number of Cities:  8,079
Status:  OPEN
Best Tour:  114,855
Best Lower Bound:  114,831

History

Date	Gap	Lower Bound	Tour
8.23.01			114,869 - Merging 10 linkerh tours. The 10 linkern runs took a total of 531,281 seconds on a 500 MHz EV6 Alpha, merging took an additional 1,847.08 seconds. The best of the 10 linkerh had length 114,911.
8.23.01	0.033%	114,831 - Established by Concorde with -C 20 (used 13 nodes in the branch-and-cut tree, 399,316 seconds on a 500 MHz EV6 Alpha).
10.10.01	0.023%		114,857 - Keld Helsgaun using variants of his LKH code. The running time was approximately 5 days on a 400 MHz Macintosh PowerBook G3.
3.27.06	0.021%		114,855 - Yuichi Nagata.

Notes

1. Concorde is our linear-programming based TSP solver.

2. linkern is an implementation of Martin, Otto, and Felten's Chained Lin-Kernighan heuristic. It is included in the Concorde code.

3. LKH is Keld Helsgaun's powerful implementation of the Lin-Kernighan heuristic.
4. linkerh is an implementation of the Lin-Kernighan heuristic, making use of a number of the ideas introduced in Keld Helsgaun's LKH code.

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