Instance Created:  April 26, 2002
Number of Cities:  21553
Status:  OPEN
Best Tour:  66529
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
3.3.03			66535 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm. The running time was 88105 seconds on a Sun Ultra 80 with four 450-MHz processors (taking the best of five runs).
3.16.03			66532 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour (12013 seconds).
7.7.04			66529 - Found by Keld Helsgaun using a variant of his LKH code.

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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