Hi,

for sure internal errors are not nice but you should not use dvar float in a CP model and you do;

```
dvar float+ percentage[indices_people][N] in booleanrange;
dvar float+ percentage_sum[indices_people];
dvar float+ percentage_tot;
dvar float+ final_percentage[indices_people] in booleanrange;
```

You should use only integer decision variables or you should use decision expressions.

In https://www.linkedin.com/pulse/making-decision-optimization-simple-alex-fleischer/ you could have a look at CPO with decimal decision variables

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[Alex] [Fleischer]

[EMEA CPLEX Optimization Technical Sales]

[IBM]

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Original Message:

Sent: Sat January 15, 2022 02:09 PM

From: Simone Mungari

Subject: Error java.lang.RuntimeException: internal error (Please notify IBM)

Hi everyone,

I'm doing a university project that is about cost sharing mechanisms. It consists of choosing people that are going to make a travel together about their preferences on a set of predefined cities. The objective function consists in a maximization of the total preferences of the selected people.

The program has also to calculate the costs that each of them (only the ones selected) will pay and this cost has to be less or equal than their maximum declared cost.

We tried some examples and all went ok, and then, with the example uploaded (AGT.dat) I obtained the error: java.lang.RuntimeException: internal error (Please notify IBM). I made this last example in order to obtain as result:

People chosen: 1, 2

Cities chosen: Rome, Paris

In the .dat file I modified the maximum_cost of the player 3 from 1000.0 to 10.0 (because otherwise the player 3 would be chosen) and then the error raised.

I think that the error is on the last constraint and this is strange because it's just a check: total_cost <= maximum_cost and in fact if I delete this constraint the program does not raise any error (but obviously the final result is wrong).

Thank you in advance,

Bests.

Simone Mungari

University of Calabria

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Simone Mungari

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