Instance Created:  May 6, 2002
Number of Cities:  498378
Status:  OPEN
Best Tour:  2,168,039
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
12.08.02			2,169,314 - Found by Keld Helsgaun using variants of his LKH code.
21.03.03			2,169,110 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
9.12.04			2,168,484 - Found by Keld Helsgaun using variants of his LKH code.
30.07.08			2,168,116 - Found by Keld Helsgaun using variants of his LKH code.
13.10.08			2,168,095 - Found by Keld Helsgaun using parallel versions of his LKH code.
06.01.09			2,168,092 - Found by Keld Helsgaun using parallel versions of his LKH code.
05.02.09			2,168,067 - Found by Keld Helsgaun using parallel versions of his LKH code.
09.11.12			2,168,061 - Found by Keld Helsgaun using parallel versions of his LKH2 code.
12.10.14			2,168,049 - Found by Xavier Clarist.
18.02.15			2,168,039 - Found by Xavier Clarist.

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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