LAUSR

Dear editor, Currently, many computationally difficult problems can be solved using very efficient methods. Some of these state-of-the-art methods have online implementations. The research question addressed herein is how sensitive are such implementations if the input data are preprocessed in a specific manner? The symmetric traveling salesman problem (sTSP), which is an NP-hard problem with many real-life applications is studied. The proposed method includes systematic transformation using rotations and reflections of the vertex order of sTSP instances. This model was used for investigating the neutrality of Concorde [1] (currently the best exact sTSP solver) and Lin–Kernighan implementation [2], both from NEOS [3] (the state-ofthe-art collection of online tools in computational optimization).