Hard to Solve Instances of the Euclidean Traveling Salesman Problemdoi:10.60507/FK2/ESZ1QZbonndata2024-05-241Hougardy, Stefan, 2024, "Hard to Solve Instances of the Euclidean Traveling Salesman Problem", https://doi.org/10.60507/FK2/ESZ1QZ, bonndata, V1Hard to Solve Instances of the Euclidean Traveling Salesman Problemdoi:10.60507/FK2/ESZ1QZHougardy, StefanbonndataHougardy, StefanHougardy, Stefan2024-05-21Computer and Information ScienceMathematical SciencesComputer and Information ScienceMathematical SciencesIn our paper Hard to Solve Instances of the Euclidean Traveling Salesman Problem (Mathematical Programming Computation (2021) 13:51-74) we construct a family of Euclidean instances for the Traveling Salesman Problem for which the integrality ratio of the subtour LP converges to 4/3. These instances turn out to be very hard to solve with exact TSP solvers. On a 200 vertex instance from our family, Concorde, the fastest known exact TSP solver, needs more than 1,000,000 times the runtime it needs for TSPLIB instances of similar size. On a 1000 vertex instance the runtime factor is already about 10^27. Here we provide instances with up to 200 vertices from our family in TSPLIB format. We also provide code for generating these instances for an arbitrary number of vertices. Finally we make all the .log-files available of the runs of Concorde we describe in our paper.<a href="http://creativecommons.org/licenses/by/4.0">CC BY 4.0</a>Hougardy, S., Zhong, X. Hard to solve instances of the Euclidean Traveling Salesman Problem. Math. Prog. Comp. 13, 51–74 (2021). https://doi.org/10.1007/s12532-020-00184-510.1007/s12532-020-00184-5Hougardy, S., Zhong, X. Hard to solve instances of the Euclidean Traveling Salesman Problem. Math. Prog. Comp. 13, 51–74 (2021). https://doi.org/10.1007/s12532-020-00184-5readme.txttext/plainTnm.cppA C++-program to generate the Tnm-instances.text/plainTnm_instances.zipAll Tnm-instances with 52 to 199 vertices.application/zipTSPLIB_logfiles.ziplog files of all Concorde runs on the TSPLIB instances as described in our paper.application/zipTnm_logfiles.zipapplication/zip