Dear OR-Community, I have searched for quite some time now, but could not find precise literature on this topic.
In a recent Paper which deals with multi-start iterated local search for the PVRPTW, I came across the following words: Context: The local search algorithm browses four neighborhoods, of which two are the following:
"2-Opt: The 2-opt move removes two arcs (i, j) and (u, v) traversed in the same route or in two distinct routes and reconnects the route(s) concerned using arcs (i, u) and (j, v). On one route, this move can be also defined by a reversal of subsequence from j to u included. When applied to two routes, two subsequences are reversed.
2-Opt*: In this move, two arcs (i, j) and (u, v) in the same route or in two routes are replaced by (i, v) and (u, j). Contrary to 2-opt, no subsequence is reversed after this operation."
My question now is: Assume that i and j, as well as u and v, are both two subsequent customers in the same route. Imagine the following tour: Depot - 1 - i - j - 4 - u - v - 7 - Depot
2-Opt* ==> Depot - 1 - i - v - 7 - Depot and j - 4 - u - j
Performing a 2-Opt* move produces an isolated subtour - how does that make sense??
Thank you! :)
Patrick
