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3

We encourage you to look at the code of jsprit, the open-source Java vehicle routing library. The jsprit approach is based on a "ruin & recreate" heuristic, also known as Adaptive Large Neighborhood Search (ALNS). The operators can be found here in the folders "ruin" and "recreate" respectively.


4

your model is not feasible and that is why you get no solution. if you comment //forall(i in cD,j in DI,t in T:t==2, f in F)cb10:recievetime[i][t]+(time[i][j]+servicetime[j][t])*K[i][j][f]-Tmax*(1-K[i][j][f])<=recievetime[j][t]; then you ll get some conflicts and relaxations like 72 [0,Infinity] [-6,Infinity] delta[1][2] 72 [0,Infinity] [-10,...


5

There is no problem in starting your ALNS with an infeasible (what you call "incomplete") solution. ALNS consists of destroying a part of the solution and then repairing it, at each iteration. Generally, destroying is done by removing a number of tours in the incumbent solution. But you can adapt the method by selecting a number of tours plus some ...


5

Altough I agree with the other answers, I think its worth mentioning that a random initial solution does not have to be feasible. When using (meta)heuristics, it is often the case that infeasible solutions are used in the search space, while the number of conflicts (the number of times a constraint is violated) is minimized in the cost function. For example, ...


7

Usually such statements mean that you should device a construction heuristic, which relies on some level of randomness. That is, if you run your construction procedure twice you should not (necessarily) get the same solution. I would in most cases, if not stated explicitly, expect the solution to be feasible to the problem (in your case it should probably ...


7

"Random solution" means the decision variables are chosen randomly. It does not usually mean ignoring feasibility constraints. So, in the case of CVRP, it would mean choosing the cities for a given route, as well as their sequence on the route, randomly. There are various ways to deal with the capacity constraint -- for example, if the next ...


6

There are multiple ways you can analyze and compare the results of heuristics/randomized search procedures. Report the average, best and worst Report the average, and standard deviation Graphically represent the results as a boxplot. When computing the average, you need to be careful when there are instances that could not be solved by the heuristic. This ...


2

There is a good description of different problem instances here. From the link: ...benchmark problems (Solomon, 1987) composed of six different problem types (C1,C2,R1,R2,RC1,RC2). Each data set contains between eight to twelve 100-node problems. The names of the six problem types have the following meaning. Sets C have clustered customers whose time ...


7

If there is one book to know about VRPs, it is: "Vehicle Routing: Problems, Methods, and Applications, Second Edition" (Paolo Toth and Daniele Vigo, 2014)


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