Instance Created:  April 26, 2002
Number of Cities:  52057
Status:  OPEN
Best Tour:  147789
Best Lower Bound:  xxx

History

Date	Gap	Lower Bound	Tour
02.02.03			147837 - Found by Keld Helsgaun, using a variant of LKH.
03.16.03			147833 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm, starting with the above tour.
18.03.03			147827 - Found by Keld Helsgaun, using a variant of LKH.
29.01.06			147825 - Found by Keld Helsgaun, using a variant of LKH.
09.08.06			147820 - Found by Keld Helsgaun, using a variant of LKH.
15.05.07			147802 - Found by Keld Helsgaun, using a variant of LKH.
07.04.08			147790 - Found by Keld Helsgaun, using a variant of LKH.
14.08.08			147789 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, Dirk Richter on an Intel Xeon 2,83 GHz by a variant of LKH based on backbone contraction.

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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