[Couenne] false infeasible

[Pietro Belotti]

Hi Abdel,

the "objective value" strings you see are from CLP, the LP solver used
by Couenne to find lower bounds. The solutions found by LP are not, in
general, feasible for the problem itself. In order to filter out the
output for less clutter, I would suggest adding the following options
to the option file:

bb_log_level 1
lp_log_level 0
nlp_log_level 0

Also, I'm not sure about the time limit and I don't know why no
solution is found, but you could try to restrict the bound tightening
by adding one or more of the following options:

feasibility_bt no
optimality_bt no
aggressive_fbbt no

Hope this helps,
Pietro


On Wed, May 13, 2015 at 10:37 AM, ALI ZAZOU Abdelkrim
<abdelkrim.ali-zazou at ensma.fr> wrote:
> Hi everyone,
>
> i'm having a problem to get results for my optimization problem that i run
> through NEOS.
> When i look at the result, i can see that the solver find the optimal
> solution, because it's the same objectif value that i get from another
> solver that finished with "optimal", but it ends on a "Couenne finished. No
> feasible solution found.".
>
> here is the text from the solver where i can see that "optimal value":
>
> "Clp0006I 7269  Obj 831436.86
> Clp0000I Optimal - objective value 831436.86
> Clp0032I Optimal objective 831436.862 - 7269 iterations time 0.522, Presolve
> 0.
>
> 08
> Clp0006I 0  Obj 831436.86 Primal inf 161.58395 (12)
> Clp0006I 4  Obj 831436.86
> Clp0000I Optimal - objective value 831436.86
> NLP0014I             2        TIME 0        0 0.035995
> Clp0000I Optimal - objective value 831436.86
> Cbc0020I Exiting on maximum time"
>
> but the solver ends with that message:
>
> "**** SOLVER STATUS     3 Resource Interrupt
> **** MODEL STATUS      14 No Solution Returned
> **** OBJECTIVE VALUE               NA          "
>
>
> So i wanted to how can i make the solver stops when it reach this "Optimal -
> objective value"??
>
> Thank you very much
> Abdel
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