Instance Created:  July 29, 2001
Number of Cities:  6,117
Status:  OPEN
Best Tour:  394,718
Best Lower Bound:  394,609

History

Date	Gap	Lower Bound	Tour
8.15.01			394,742 - found by running linkerh to produce 10 tours, and then merging the tours using tmerge. The 10 linkerh runs took a total of 30,079.59 seconds on a 500 MHz EV6 Alpha and the tmerge run took an additional 24.10 seconds. The best of the linerh tours had length 394,797.
8.15.01			394,726 - found by running Keld Helsgaun's LKH code 10 times, each with 6117 trials, and choosing the best tour. The total running time was 35,787.17 seconds on a 1.33 GHz AMD Athlon processor.
8.16.01	0.046%	394,543 - Concorde -C 24, with Cplex 6.5 LP solver, 351 hours, 500 MHz EV6 Alpha processor, the branch-and-cut run created 631 nodes in the search tree
8.17.01	0.044%		394,718 - found by running LKH to produce 10 tours, and then merging the tours using tmerge. The 10 LKH runs took a total of 52,196.23 seconds on a 500 MHz EV6 Alpha and the tmerge run took an additional 17.63 seconds. The best of the LKH tours had length 394,730.
3.13.02	0.027%	394,609 - Concorde -C 24, with QSopt LP solver, 1,556 hours, AMD Athlon 1900+ processor, the branch-and-cut run created 2,369 nodes in the search tree. The root LP was run with -C 40; the branching was carried out in parallel on a network of 15 AMD workstations

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.
4. linkerh is an implementation of the Lin-Kernighan heuristic, making use of a number of the ideas introduced in Keld Helsgaun's LKH code.

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