1f1f598314
The original tutorial link[http://paradiseo.gforge.inria.fr/index.php?n=Doc.Tutorials] is broken. I found the archive from here: https://web.archive.org/web/20210119160107/http://paradiseo.gforge.inria.fr/index.php?n=Doc.Tutorials
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2.7 KiB
Markdown
64 lines
No EOL
2.7 KiB
Markdown
# How to use Iterated Local Search
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In this lesson, an Iterated Local Search is presented. The Tabu Search of the Lesson 4 is used with an order neighborhood based on a shift operator, to solve the Queen problem.
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1. Iterated Tabu Search on the Queen problem.
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2. Exercise
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## 1. Iterated Tabu Search (example on the Queen problem)
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As in Lesson 4, you have to define a Solution, the method to initialize and evaluate it. Then you have to define a Tabu Search.
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Declaration of the Tabu Search:
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```c++
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moTS<shiftNeighbor> ts(orderShiftNH, fullEval, shiftEval, 1, 7);
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```
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To use a simple Iterated Local Search, a mutation operator is needed. So the swap mutation defined in EO is used:
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```c++
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eoSwapMutation<Queen> mut;
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```
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Now, a simple Iterated Tabu Search can be declared as follow:
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```c++
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moILS<shiftNeighbor> localSearch1(ts, fullEval, mut, 3);
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```
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This constructor has got 4 parameters:
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1. a local search (ts)
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2. a full evaluation function (fullEval)
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3. a mutation operator (mut)
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4. a number of iterations (3)
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**localSearch1** performs the Tabu Search 3 times. The first solution of each iteration(except the first one) is obtained by applying the mutation operator on the last visited solution.
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A constructor allows to specify the continuator. **_Be carefull_**, the continuator must be templatized by a "moDummyNeighbor":
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```c++
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moIterContinuator<moDummyNeighbor<Queen> > cont(4, false);
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```
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The explorer of the Iterated local search don't use its own neighborhood. Here, the neighborhood of the Tabu Search is used. But to respect the conception, we create a "moDummyNeighbor" using as template for Iterated Local Search.
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An Iterated Tabu Search with this continuator can be declared as:
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```c++
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moILS<shiftNeighbor> localSearch2(ts, fullEval, mut, cont);
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```
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A general constructor is available allowing to specify the perturbation operator and the acceptance criteria. First, you have to declare a perturbation operator:
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```c++
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moMonOpPerturb<shiftNeighbor> perturb(mut, fullEval);
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```
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And, the acceptance criteria:
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```c++
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moSolComparator<Queen> solComp;
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moBetterAcceptCrit<shiftNeighbor> accept(solComp);
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```
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Finally, the Iterated Local Search can be declared as:
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```c++
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moILS<shiftNeighbor> localSearch3(ts, fullEval, cont, perturb, accept);
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```
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You can test these three algorithms by changing problem sizes(use parameter file or the option --vecSize=X on command line to execute "testILS"). It prints the initial and the final solutions.
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## 2. Exercise
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* Try to implement an Iterated Hill Climbing on the Queen problem with these caracteristics:
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1. Hill Climbing with a "moShiftNeighborhood" and a "moTrueContinuator"
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2. Iterated Local Search using a "moIterContinuator" and a "moNeighborhoodPerturb" with a "moSwapNeighborhood". |