Instance Created:  July 29, 2001
Number of Cities:  8,246
Optimal Value:  206,171
Solved:  March 22, 2009
Solution Method:  Concorde

History

Date	Gap	Lower Bound	Tour
8.23.01			206,171 - Best tour from 40 runs of LKH (n trials per run). The 40 LKH runs took a total of 304,886 seconds on a 500 MHz EV6 Alpha. Merging the tours (52.99 seconds) did not make an improvement.
8.27.01	0.021%	206,128 - Established by Concorde with -C 20 (used 1,175 nodes in the branch-and-cut tree, 743,371 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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