[Cbc] Multi Solutions for an LP solve using CBC solver

[Aby Subin]

Thanks Haroldo for the reply. But here, even pre-processing was turned off ( along with cut and heuristics) . Please refer the commands those were executed which are mentioned in original message. So, was expecting more solutions. Could you tell if I am doing something wrong here?

Regards
Aby

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________________________________
From: Haroldo Gambini Santos <haroldo at ufop.edu.br>
Sent: Tuesday, March 3, 2020 11:11:02 PM
To: Aby Subin <aby.subin at nutanix.com>; cbc at list.coin-or.org <cbc at list.coin-or.org>
Subject: Re: [Cbc] Multi Solutions for an LP solve using CBC solver

Hi,

This options saves multiple solutions IF in the search process they are
found.

In this case pre-processing already finds the optimal one, so the search
stops.

Em 3/1/20 1:57 PM, Aby Subin escreveu:
> Hi all,
>
> As per the
> https://urldefense.proofpoint.com/v2/url?u=https-3A__list.coin-2Dor.org_pipermail_cbc_2012-2DFebruary_000766.html&d=DwIDaQ&c=s883GpUCOChKOHiocYtGcg&r=Bak3-3UtIw0QEwx645L7Agnx0N5k3avy8k01f01AiGY&m=d21DVhe16ObDeSF_FYf8vkL9Kd-QLsztSlwrxN_lkEk&s=Sd9g8RxyAgAmqFLNH-DxEQ22t7-XPhtuQLspqJtEqbw&e= , we
> are supporting multiple solutions in CBC. But on trying out a
> sample/test lp file, it is not working as expected
> (tried with both disabling and enablign options for preprocessing,
> heur, cutoff). The LP file content is as follows:
> "
>
> \Problem name:
>
> Minimize
>
> obj: 2 x0 + 5 x1 + 3 x2
>
> Subject To
>
> cons0:x0 + x1 + x2 = 1
>
> Bounds
>
> 0 <= x0 <= 1
>
> 0 <= x1 <= 1
>
> 0 <= x2 <= 1
>
> End
>
>
> "
>
>
> I was testing the same using CBC shell command. The list of commands
> tries out as follows
>
>
> Coin:import test.lp
>
> Coin:maxSaved 3
>
> maxSavedSolutions was changed from 0 to 3
>
> Coin:cuts off
>
> Option for cutsOnOff changed from on to off
>
> Coin:heur off
>
> Option for heuristicsOnOff changed from on to off
>
> Coin:preprocess off
>
> Option for preprocess changed from sos to off
>
> Coin:solve
>
> Presolve 0 (-1) rows, 0 (-3) columns and 0 (-3) elements
>
> Empty problem - 0 rows, 0 columns and 0 elements
>
> Optimal - objective value 2
>
> After Postsolve, objective 2, infeasibilities - dual 0 (0), primal 0 (0)
>
> Optimal objective 2 - 0 iterations time 0.002, Presolve 0.00
>
> Coin:solu bestSol.txt
>
> Coin:nextB 1bestSol.txt
>
> All alternative solutions printed
>
>
>
> Could you please let me know on where I am missing the solutions?
>
>
> Regards
>
> Aby
>
>
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--
=============================================================
Haroldo Gambini Santos
Computing Department
Universidade Federal de Ouro Preto - UFOP
email: haroldo at ufop.edu.br
home/research page: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.decom.ufop.br_haroldo&d=DwIDaQ&c=s883GpUCOChKOHiocYtGcg&r=Bak3-3UtIw0QEwx645L7Agnx0N5k3avy8k01f01AiGY&m=d21DVhe16ObDeSF_FYf8vkL9Kd-QLsztSlwrxN_lkEk&s=W8s7lsrnqrWfNnFykaiz33xwsKskK5foOFqUpkA28Vg&e=


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the most important.
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