Instance Created:  July 29, 2001
Number of Cities:  10,639
Optimal Value:  520,527
Solved:  April 19, 2009
Solution Method:  Concorde

History

Date	Gap	Lower Bound	Tour
8.25.01			520,527 - Found by merging 40 LKH (each with n trials). The 40 LKH runs took a total of 520,540 seconds on a 500 MHz EV6 Alpha, and the merge took an additional 167.73 seconds. The best of the LKH tours had length 520,540.
8.28.01	0.028%	520,383 - Established by Concorde with -C 20 (used 533 nodes in the branch-and-cut tree, 652,558 seconds on a 500 MHz EV6 Alpha).

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.

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