Instance Created:  April 26, 2002
Number of Cities:  3056
Status:  Optimal (see summary page)
Best Tour:  8258
Best Lower Bound:  8258

History

Date	Gap	Lower Bound	Tour
6.10.02			8262 - Best of 10 runs of LKH, each with n trials. Total running time 3682 seconds on an AMD Althlon 1900+ processor (1.6 GHz).
2.2.03			8260 - Found by Keld Helsgaun, using a variant of LKH.
2.26.03			8258 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm. The running time was 7430 seconds on a Sun Ultra 80 with four 450-MHz processors (taking the best of five runs).

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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