[Scip] including a solution found by an heuristic

Alessia Violin aviolin at ulb.ac.be
Wed Jun 19 12:25:37 MEST 2013


Hello,

yes, the solution is for the transformed problem, and with the function 
SCIPgetSolTransObj(scip,sol) I get the correct value for the objective 
function in the transformed space, or with SCIPgetSolOrigObj(scip,sol) 
in the original space.

I tried your suggestions:
- adding #define SCIP_DEBUG to sol.c does not give any additional output
- printing out the return of solOfInterest() in SCIPprimalTrySolFree() 
gives me TRUE. Then I tried to add another printf to check the value 
"feasible" after the call of SCIPsolCheck and I get FALSE, so I suppose 
the problem is here, but I don't understand as I don't get any printing 
of violating constraints/bounds etc and I checked that it's better than 
the current one and feasible.

Thanks again,

best,

Alessia




On 06/18/2013 05:37 PM, Ambros Gleixner wrote:
> Hi Alessia,
>
> I suppose the solution lives in the transformed problem, does it?
>
> Maybe you can get some additional information if you add
>
> #define SCIP_DEBUG
>
> at the very top of src/scip/sol.c and recompile.  If not, you could 
> add a manual debug printf to SCIPprimalTrySolFree() in primal.c to see 
> whether solOfInterest() returns TRUE.
>
> Ambros
>
>
>
> Am 18.06.2013 16:59, schrieb Alessia Violin:
>> Hello,
>>
>> I am trying to implement a simple heuristic into my branch-and-price,
>> and I am having some troubles when adding the new solution found with
>> the function SCIPtrySolFree(scip, &sol, TRUE, TRUE, TRUE, TRUE, 
>> &success).
>>
>> The "success" parameter after this call is always false, even if I don't
>> get any violation of constraints/bounds etc printed out. I also manually
>> checked the solution found by the heuristic, and it's feasible, not
>> violating the branching constraints in the current node, and better that
>> the current primal bound. So I don't know where/what to search more to
>> avoid this and to make scip using this new solution...
>>
>> If needed I can of course provide more details on my implementation.
>>
>> Thanks in advance for any help,
>>
>> best,
>>
>> Alessia
>>
>

-- 
Alessia Violin
Service Graphes et Optimisation Mathématique (G.O.M.)
Université Libre de Bruxelles
C.P. 210/01
Boulevard du Triomphe
B-1050 BRUXELLES
Tel: 02 650 58 80 - Fax: 02 650 59 70
Email: aviolin at ulb.ac.be
Webpage: http://homepages.ulb.ac.be/~aviolin/



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