Originally posted by: bgokgur

Hi all,

We are working on CP Model. After developing the model, we faced to a problem like :

-internal error (Please notify Ilog)

Does anyone know the meaning of this error ? or

What is your advice for that problem ?
Thank you,
Burak
#CPOptimizer
#DecisionOptimization

Originally posted by: SystemAdmin

Hello Burak.

Hard to tell without more details. Could you be more specific? What product and what version are you using? What is your platform?
Also, could you give us your model, or at least a part of it which exhibits the problem?

Thanks, Petr
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#DecisionOptimization

Originally posted by: bgokgur

First of all, thanks for your response.

I am using OPL 6.1.1 CP Optimizer.

I think that the reason of the problem is "pulse" constraint.

Because I deleted all constraints and only "pulse" constraint is left but OPL gave an error message that I posted here.

Again,

Thanks for your help
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#DecisionOptimization

Originally posted by: rdumeur

Dear Burak,

Could you please provide the minimal model that exhibits the problem with the pulse constraint?
It would help us very much understanding the problem.
Thank you very much in advance,
#CPOptimizer
#DecisionOptimization

Originally posted by: bgokgur

CP Model is shown below.

constraints{

forall(i in vehicle)
sum(j in trip) pulse(Trip[j],demand[j]) <= capacity[i] ;
forall(j in trip)
alternative(Trip[j], all(v in VS: v.j==j)Set_Trip[v]);

forall(j in trip)
startOf(Trip[j]) == release[j] ;

forall(j in trip)
endOf(Trip[j]) == departure[j] ;
};

I used "pulse" constraint to satisfy demand and our resource is cumulative because resource can take any activity according to its capacity.

Thank you for your response,

Burak
#CPOptimizer
#DecisionOptimization

Originally posted by: ChrisBr

Hello Burak,

Despite the fact that it's difficult to investigate with this short piece of code, I would suggest you to test something.

Try to define your cumul-function before the constraints block:

cumulFunction f = sum(j in trip) pulse(Trip[j],demand[j]);

Then write your constraint by this way:

forall(i in vehicle) f <= capacity[i];

By the way, it would be interesting to know how many trips and how many vehicles are there in your model.

Let us know if this solves your problem please.

I hope this helps,

Chris.
#CPOptimizer
#DecisionOptimization

Originally posted by: bgokgur

Hello Chris,

I updated the model in the way that you said and the model works.

However, I did not understand what is the difference between using pulse with "cumulative function expression" and pulse without "cumulative function expression" ? What are their effects on the CP solver or ILOG ?

Thank you for your support,
Burak.
#CPOptimizer
#DecisionOptimization

Originally posted by: ChrisBr

Hi Burak,

Indeed, from a modeling point of view there isn't any difference between both formulations.

But depending on the way your model is written, the cumul-function is not built by the same process.
In a loop like the following:

forall(i in vehicle) sum(j in trip) pulse(Trip[j],demand[j]) <= capacity[i] ;

despite the fact that the cumul-function doesn't depend on "i", it is built at each iteration of the forall; this could lead to a big memory consumption.

I also noted that you are using an old version of OPL/CPOptimizer. Please try using a more recent one.
If the problem persists, please provide us your model so that we would be able to investigate from where it comes.

I hope this clarify,

Chris.
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#DecisionOptimization