Instance Created:  April 26, 2002
Number of Cities:  28534
Status:  OPEN
Best Tour:  78562
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
2.2.03			78577 - Found by Keld Helsgaun, using a variant of LKH.
3.10.03			78575 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm. The running time was 99109 seconds on a Sun Ultra 80 with four 450-MHz processors (taking the best of five runs).
3.16.03			78571 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm, starting with the above tour (14270 seconds).
18.3.03			78567 - Found by Keld Helsgaun, using a variant of LKH.
7.4.08			78563 - Found by Keld Helsgaun, using a variant of LKH.
14.7.08			78562 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, and Dirk Richter, using a variant of LKH.

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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