Instance Created:  April 26, 2002
Number of Cities:  56769
Status:  OPEN
Best Tour:  158078
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
2.2.03			158122 - Found by Keld Helsgaun, using a variant of LKH.
16.3.03			158116 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
21.3.03			158114 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
5.3.03			158110 - Found by Keld Helsgaun, using a variant of LKH.
7.4.08			158090 - Found by Keld Helsgaun, using a variant of LKH.
14.7.08			158084 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, and Dirk Richter, using a variant of LKH.
25.7.08			158082 - Found by Keld Helsgaun, using a variant of LKH-2.
9.2.11			158078 - Found by Yuichi Nagata.

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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