[Couenne] Lower/Upper bounds variables

[Pietro Belotti]

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
>>
>
>