Instance Created:  April 26, 2002
Number of Cities:  17845
Status:  OPEN
Best Tour:  48092
Best Lower Bound:  48083

History

Date	Gap	Lower Bound	Tour
10.6.02			48100 - Best of 10 runs of LKH, each with n trials. Total running time 218988 seconds on an AMD Althlon 1900+ processor (1.6 GHz).
3.3.03			48097 - Found by Hung Dinh Nguyen using a parallel hybrid genetic algorithm. The running time was 64687 seconds on a Sun Ultra 80 with four 450-MHz processors (taking the best of five runs).
16.3.03			48094 - Found by Hung Dinh Nguyen using a hybrid genetic algorithm. The running time was 12507 seconds on a Sun Ultra 80, starting from the above tour.
20.3.08			48093 - Found by Changxing Dong, Gerold Jaeger, Paul Molitor, Dirk Richter by a variant of LKH based an backbone contraction. The running time was 110100 seconds on a AMD Opteron Processor (2.6 GHz).
28.4.08			48092 - Found by Keld Helsgaun, using a parallel memetic variant of LKH.
29.4.17	0.019%	48083 - Concorde (-Z1 -J4), using CPLEX as an LP solver. Wall-clock time for the branch-and-cut search was 3.0 days on a 48-core Intel Xeon E5-2620 @ 2.00GHz cluster; search tree contained 2,573 nodes.

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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