[Scip] Fwd: stop condition of pricing routine

[Gerald Gamrath]

Hi Mattia,

I also understood your question the other way around, so probably at
least the first part of my last answer won't help you much.
The only criterion SCIP uses to determine whether the pricing process is
finished or the pricers should be called again is whether new variables
were added in the last pricing round. Perhaps this could be changed, so
that the pricing is continued after you changed your trust region, but
could you first explain how you do this if you must not enlarge the
feasible region at a node compared to its father node?

If you do it like I wrote, copy the LP within your pricer and impose the
trust region just in this copy, I think the problem with SCIP stopping
the pricing process too early should not occur, since you can move the
trust region and look for new variable until you find some or you proved
that none exists.

Best regards,
Gerald

Am 28.07.2010 11:59, schrieb Mattia Barbieri:
>
>
> ---------- Forwarded message ----------
> From: *Mattia Barbieri* <barbieri.mattia at gmail.com
> <mailto:barbieri.mattia at gmail.com>>
> Date: 28 July 2010 11:57
> Subject: Re: [Scip] stop condition of pricing routine
> To: Martin Bergner <mbergner at mathematik.tu-darmstadt.de
> <mailto:mbergner at mathematik.tu-darmstadt.de>>
>
>
> Hi Martin,
>  my problem is the opposite: it might happen (and that is the case)
> that no variables with negative reduced costs are found, so the pricer
> leave the node (no improvement due to new reduced cost columns). I
> want instead that the pricer iterates AGAIN, because, even if no
> variables have been added to the Master Problem, the dual variables
> associated will change anyway due to the penalties applied, so it is
> possible that a new column will be found at the next iteration (may be
> a misprice column, but this case is considered by the method I use).
>
>   Regards,
>
>
> On 28 July 2010 11:34, Martin Bergner
> <mbergner at mathematik.tu-darmstadt.de
> <mailto:mbergner at mathematik.tu-darmstadt.de>> wrote:
>
>     Hello Mattia,
>
>     I forgot: There is a method SCIPdeactivatePricer, would that work?
>
>     Regards,
>     Martin
>
>
>
>
> -- 
> Mattia Barbieri
> barbieri.mattia at gmail.com <mailto:barbieri.mattia at gmail.com>
>
>
>
> -- 
> Mattia Barbieri
> barbieri.mattia at gmail.com <mailto:barbieri.mattia at gmail.com>
>
>
> _______________________________________________
> Scip mailing list
> Scip at zib.de
> http://listserv.zib.de/mailman/listinfo/scip
>   

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listserv.zib.de/mailman/private/scip/attachments/20100728/5cd015f3/attachment.html