Instance Created:  April 26, 2002
Number of Cities:  16928
Status:  OPEN
Best Tour:  52850
Best Lower Bound:  52838

History

Date	Gap	Lower Bound	Tour
6.10.02			52856 - Best of 10 runs of LKH, each with n trials. Total running time 208364 seconds on an AMD Althlon 1900+ processor (1.6 GHz).
2.2.03			52855 - Found by Keld Helsgaun, using a variant of LKH.
3.3.03			52850 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm. The running time was 47939 seconds on a Sun Ultra 80 with four 450-MHz processors (taking the best of five runs).
1.5.17	0.023%	52838 - Concorde (-Z1 -J4), using CPLEX as an LP solver. Wall-clock time for the branch-and-cut search was 2.9 days on a 48-core Intel Xeon E5-2620 @ 2.00GHz cluster; search tree contained 2,055 nodes.

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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