Re: [eclipse-clp-users] How to get non-optimal solution from eplex with timeout

From: Sergii Dymchenko <kit1980_at_...6...>
Date: Sun, 14 Jul 2013 17:59:41 -0700
Thanks for the prompt response, Kish!

I should had read the docs about abort_handler more carefully. My problem
is a MIP problem, and getting initial solution takes couple of minutes.

Sergii.


On Sun, Jul 14, 2013 at 4:49 PM, Kish Shen <kisshen_at_...5...> wrote:

> Hi Sergii,
>
>
> On 14/07/2013 20:48, Sergii Dymchenko wrote:
>
>> Hi,
>>
>> How can I get non-optimal solution from eplex with timeout?
>>
>>
> You don't need to do anything, the best non-optimal solution (if
> available) will be returned automatically.
>
> If you are solving a linear problem, then the first solution found with
> the dual method will be the optimal solution, so there are no sub-optimal
> solutions in such cases.
>
>
>  I setup eplex with:
>>      eplex_solver_setup(min(Obj), _, [timeout(10), abort_handler(ab)],
>> []),
>> and after timeout my handler `ab` is called.
>>
>> But what to do in `ab` handler to get non-optimal solution?
>>
>>
> The abort_handler handles the abort case, where a solve aborts without
> finding any feasible solution, as described in the reference documentation
> for eplex_solver_setup/4:
>
> >abort_handler(+Goal)
> >    Specifies a user defined goal Goal to handle the case when the
> >    external solver aborted without finding any solution. Goal would be
> >    run in place of raising the default eplex_abort event.
>
> So there is no solution to get, and it is not known if the problem is
> feasible.
>
>
>  I can get best or worst objective bounds with `eplex_get(best_bound, X)`,
>> but `eplex_get(typed_solution, Vars)` just fails.
>>
>>
> The best and worst bounds provide bounds on the any optimal solution, but
> on its own does not imply there is any solution.
>
>
> Cheers,
>
> Kish
>
>  Or maybe using abort_handler for getting non-optimal solution is not a
>> good
>> idea and there is a better way?
>>
>> Sergii.
>>
>>
>>
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Received on Mon Jul 15 2013 - 00:59:49 CEST

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