Originally posted by: Stefano_TUE

Hello,

I have a problem for the input data to the following problem:

http://pic.dhe.ibm.com/infocenter/oplinfoc/v6r3/topic/ilog.odms.ide.help/examples/html/opl/models/TravelingSalesmanProblem/tsp.mod.html

It is a TSP formulation from the OPL samples.

My doubt is how the data of the instance should be written for the tuple:

034: tuple Subtour { int size; int subtourCities; }
035: {Subtour} subtours = ...;

This tuple is related to the subtour elimination constraints.

If you have any TSP.dat, it would be very useful.

Thanks
Stefano
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Originally posted by: davidoff

Hello

In the sample, the subtours are initially set to an empty collection in the params.dat file. Then subtours are detected in the postProcess and we keep the smallest subtour and resolves the model.

You can display the last subtour added to the MIP

dat.subtours.add(opl.newSubtourSize, opl.newSubtour); writeln(
"Last subtour added : ",Opl.last(dat.subtours));
//add this to display the last subtour

For instance, the first subtour is

<3 [0 0 14 0 0 0 0 0 0 0 0 0 0 15 3 0 0]>

which means that we have found a subtour of 3 cities, namely cities 3 (with successor 14) ,14 (with successor 15) and 15 (with successor 3)

If you want to add initial known subtours, you can set additional sets in params.dat

David
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Originally posted by: SystemAdmin

forall (s in subtours)
sum (i in Cities : s.subtour[i] != 0)
x[<minl(i, s.subtour[i]), maxl(i, s.subtouri])>
<= s.size-1;
excuse me, i have some questions obout the code obve. Could you some explainnation about how the constraints make effects on the TSP problem.
I would aprreciate your help very much.
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Originally posted by: max__x

Hello, David

I have the same problems as Stefano,  

does this what you mean here ?

and set the initial subset to be empty?

Is the code used in CPLEX?

because there still some mistake in the code. such as the unexpected "." after dat  and writeln I bold.

 

 

 

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same thread at https://www.ibm.com/developerworks/community/forums/html/topic?id=45075e99-c6b9-447f-94da-4b8124f0662c&ps=25

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