Instance Created:  April 26, 2002
Number of Cities:  13584
Optimal Value:  37083
Solved:  April 19, 2017

History

Date	Gap	Lower Bound	Tour
10.6.02			37085 - Best of 10 runs of LKH, each with n trials. Total running time 130015 seconds on an AMD Althlon 1900+ processor (1.6 GHz).
2.2.03			37084 - Found by Keld Helsgaun, using a variant of LKH.
28.3.08			37083 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, Dirk Richter by a variant of LKH based an backbone contraction. The running time was 676800 seconds on an Intel Xeon E5440 Processor (2.83 GHz).
19.4.17	Optimal	37083 - Concorde (-Z1 -J4), using CPLEX as an LP solver. Wall-clock time for the branch-and-cut search was 1.8 days on a 48-core Intel Xeon E5-2620 @ 2.00GHz cluster; search tree contained 5,089 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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