Instance Created:  April 26, 2002
Number of Cities:  38478
Status:  OPEN
Best Tour:  108318
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
2.2.03			108338 - Found by Keld Helsgaun, using a variant of LKH.
16.3.03			108334 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
18.3.03			108332 - Found by Keld Helsgaun, using a variant of LKH.
15.5.07			108327 - Found by Keld Helsgaun, using a variant of LKH.
27.5.08			108318 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, and Dirk Richter using a variant of LKH. The running time was 482220 seconds on an AMD Opteron (2.6 GHz).

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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