Instance Created:  April 26, 2002
Number of Cities:  10150
Optimal Value:  28387
Solved:  April 17, 2017

History

Date	Gap	Lower Bound	Tour
10.6.02			28388 - Best of 10 runs of LKH, each with n trials. Total running time 53022 seconds on an AMD Althlon 1900+ processor (1.6 GHz).
16.3.03			28387 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm. The running time was 9089 seconds on a Sun Ultra 80 (450-MHz processor), starting from a tour found from an earlier run with a parallel version of the algorithm (22752 seconds with four processors).
17.04.17	Optimal	28387 - Concorde (-Z1 -J4), using CPLEX as an LP solver. Wall-clock time for the branch-and-cut search was 0.9 days on a 48-core Intel Xeon E5-2620 @ 2.00GHz cluster; search tree contained 1,889 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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