[Cbc] Improving performance for binary model

[Pieter Zieschang]

Hi,

try with : 

/cbc Problem.mps -keepNames=on -threads=8 -dualt=1e-06 -perturb=on 
-pertvalue=61 -ratiogap=0.001 -multiple=8 -preprocess=aggregate 
-initialsolve -export=Problem_initialsolved.mps


I wonder if there is any way to reduce the problem any further?
The cbc log often prints reduced to ... messages - any chance to do that 
without completely solving? Or is  "initialsolve" all thats possible here?

(The file size shrinks but solving speed of the initialsolved MPS is not 
much better, only a little bit in my case)



Mit freundlichen Grüßen / Kind regards
________________________________________

Pieter Zieschang

Modis IT Outsourcing GmbH
Atriumstraße 1, 04315 Leipzig

Amtsgericht Düsseldorf: HRB 78227
Geschäftsführer: Martin Wimmer, Andreas Buchelt, Jörg Brinkmann

ito.modis.de






From:   "Rui Patrocínio" <ruip at siscog.pt>
To:     cbc at list.coin-or.org
Date:   27.11.2019 16:28
Subject:        Re: [Cbc] Improving performance for binary model
Sent by:        "Cbc" <cbc-bounces at coin-or.org>



Hi John and others,
 I'm trying to export the preprocessed model with '-preprocess save' 
(getting a 'presolved.mps') file. Redoing the preprocess on the model of 
the presolved.mps file is not making it smaller. It's possible that I'm 
missing something. Is there any other way to export the preprocessed model 
to reproduce what you are seeing?
Best regards,
Rui

On 11/23/2019 10:00 AM, John Forrest wrote:
My guess is that Cbc is very bad at handling symmetry.  There is a lot of 
symmetry and trying some of the ways that Cbc can deal with symmetry I can 
get a solution of 296773 fairly quickly, but after an hour it does not 
seem to be closing the gap.  The other area where Cbc is failing somewhat 
is preprocessing - if I export the model several times (each time doing 
presolve) then I can make it smaller - this obviously wrong. 

John Forrest 

On 22/11/2019 15:44, Rui Patrocínio wrote: 
Hi, 

  I'm trying to solve one instance of a problem that is taking a long time 
to obtain a good solution. Since all variables are binary, probing and 
implication cuts are doing some work and RINS and Vnd are apparently also 
improving solutions. For other instances of the problem we are solving, 
CBC has an acceptable performance but for this instance apparently there's 
something going wrong (~20 seconds to get the optimum solution with a 
commercial solver versus never getting the optimum solution with CBC). 

  If someone can take a look at the model and give me a hint of what is 
going on, I would appreciate it. 

  The model is at 
https://drive.google.com/open?id=1bd4jWONmoyAKIi0oLa-AU-ZTu7_8qhb6 

-- 
SISCOG - Sistemas Cognitivos, SA 

*Rui Patrocínio* 

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-- 

Rui Patrocínio
Scheduling Team Leader

SISCOG - Sistemas Cognitivos, SA
A Campo Grande, 378 - 3º, 1700-097 Lisboa, Portugal
T +351 217 529 100 W www.siscog.pt

Optimising the resources of the world


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