[Couenne] Lower/Upper bounds variables

[Luca Mencarelli]

Dear Pietro,

I've done other experiments with the code, but I cannot retrieve
the values of the decision variables corresponding to the Upper Bound
provided by Couenne.

Thanks very much. Best regards,
Luca

> Dear Pietro,
>
> I attach the model and the output files. I get an upper_bound = -210.89,
> while the upper bound provided by Couenne (version 0.4.8) is -286.95.
> The original problem is a maximization one.
>
> Thanks again. Best,
> Luca
>
> --
> Luca Mencarelli
> PhD Candidate at LIX, Ecole Polytechnique
> 91128 Palaiseau CEDEX, France
> Office: 2072 (Bâtiment Alan Turing, second floor)
> LIX e-mail address: mencarelli at lix.polytechnique.fr
> INRIA e-mail address:  luca.mencarelli at inria.fr
>
>
>
>> Hi Luca,
>>
>> this should not happen, it might be a bug. Can you send me the model
>> (a .nl file should suffice)? I suspect the constant term of the
>> objective function might be ignored. Also, what version of Couenne are
>> you using?
>>
>> Pietro
>>
>> On Mon, May 18, 2015 at 4:55 PM, Luca Mencarelli
>> <mencarelli at lix.polytechnique.fr> wrote:
>>> Dear Pietro,
>>>
>>> First of thanks very much for the answer. However in the .sol file I
>>> found
>>> the same values as the one I obtain via the display command. But when I
>>> recompute
>>> the objective function with these values, it is less than the upper
>>> bound
>>> provided
>>> by Couenne.
>>>
>>> Best,
>>> Luca
>>>
>>> --
>>>
>>> Luca Mencarelli
>>> PhD Candidate at LIX, Ecole Polytechnique
>>> 91128 Palaiseau CEDEX, France
>>> Office: 2072 (Bâtiment Alan Turing, second floor)
>>> LIX e-mail address: mencarelli at lix.polytechnique.fr
>>> INRIA e-mail address:  luca.mencarelli at inria.fr
>>>
>>>
>>>
>>>> Hi Luca,
>>>>
>>>> when Couenne stops before closing the gap, the best feasible MINLP
>>>> solution found (if any) is saved in a file with the same name as the
>>>> input file but with extension .sol (which is the format read by AMPL).
>>>> So the answer is yes for the upper bound if at least one solution is
>>>> found.
>>>>
>>>> However, this does not make much sense for the lower bound, given that
>>>> it's obtained by a relaxation of the MINLP (and would hence be
>>>> infeasible) and is related to the whole branch-and-bound search tree
>>>> rather than a specific subproblem. Hence no solution is available for
>>>> the lower bound.
>>>>
>>>> Hope this helps,
>>>> Pietro
>>>>
>>>>
>>>> On Mon, May 18, 2015 at 11:05 AM, Luca Mencarelli
>>>> <mencarelli at lix.polytechnique.fr> wrote:
>>>>> Hi,
>>>>>
>>>>> If Couenne did not succeed in solving a problem to optimality, it's
>>>>> possible to
>>>>> retrieve the values of the decision variables corresponding to the
>>>>> lower
>>>>> and to
>>>>> the upper bounds provided by the solver?
>>>>>
>>>>> Thanks. Best,
>>>>> Luca
>>>>>
>>>>> --
>>>>> Luca Mencarelli
>>>>> PhD Candidate at LIX, Ecole Polytechnique
>>>>> 91128 Palaiseau CEDEX, France
>>>>> Office: 2072 (Bâtiment Alan Turing, second floor)
>>>>> E-mail address: mencarelli at lix.polytechnique.fr
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Couenne mailing list
>>>>> Couenne at list.coin-or.org
>>>>> http://list.coin-or.org/mailman/listinfo/couenne
>>>>
>>>
>>>
>>
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