Instance Created:  April 26, 2002
Number of Cities:  43748
Status:  OPEN
Best Tour:  125183
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
2.2.03			125210 - Found by Keld Helsgaun, using a variant of LKH.
16.3.03			125205 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
3.5.03			125202 - Found by Keld Helsgaun, using a variant of LKH.
25.7.08			125185 - Found by Keld Helsgaun, using a variant of LKH.
13.11.09			125184 - Found by Masafumi Kuroda using a parallel hybrid genetic algorithm based on Lin-Kernighan. The run was executed on a cluster of 12 machines (48 CPU, 2.8-GHz Xeon). The running time was 1,353,111 seconds.
17.5.10			125183 - Found by Keld Helsgaun, using a variant of LKH.

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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