[Cbc] Cbc CLI Infeasible Error

[Matthew Gidden]

Hi John,


On Wed, Jul 30, 2014 at 12:11 PM, John Forrest <john.forrest at fastercoin.com>
wrote:

>  Matthew,
>
> Should be easy to fix - looks like a really stupid bug.
>
> If I change the lower bounds on y,z to 2,1 it works!  As rounding up
> should be first thing that happens, you can see why I say stupid.
>
Ok, thanks John! I can change my bounds on my unit test for now, but I'm
glad I was able to bring this to your attention. Thanks again for looking
into it.

>
> John Forrest
>
>
> On 30/07/14 16:20, Matthew Gidden wrote:
>
> Hi all,
>
>  I've been posting a lot recently.. first of all, thank you for replying!
>
>  I've unit tested my application pretty vigorously, and a Cbc API unit
> test broke when I moved to the CLI implementation. Specifically, I set up
> the following toy problem:
>
>  min 2x + 0.5y + 1.8z
> st     x  +     y            > 4.4
>                    y +     z  < 3.1
> x in [1.3, 5], y in [1.7, 5], z in [0.4, 5]
> y, z integer
>
>  The unit test originally passed using the OsiCbcSolverInterface's
> initial solve and branch and bound methods. I updated it to use an
> OsiClpSolverInterface that is fed a CbcModel and call CbcMain0/1 on said
> model. The unit test now fails with the following relevant output:
>
>> Welcome to the CBC MILP Solver
>> Version: 2.8.7
>> Build Date: Dec 28 2013
>> command line - exchng -solve -quit (default strategy 1)
>> Continuous objective value is 5.47 - 0.00 seconds
>> Cgl0000I Cut generators found to be infeasible! (or unbounded)
>> Pre-processing says infeasible or unbounded
>
>
>  To double check that indeed a feasible solution existed, I solved the
> maximization form of the same instance. Attached are MPS files for the max
> and min forms, and I have verified the same behavior using the cbc CLI
> (i.e., min is returned as infeasible and max solves).
>
>  I'm curious if anyone can replicate this and/or has any advice.
>
>  Cheers,
>
>  --
> Matthew Gidden
> Ph.D. Candidate, Nuclear Engineering
> The University of Wisconsin -- Madison
> Ph. 225.892.3192
>
>
> _______________________________________________
> Cbc mailing listCbc at list.coin-or.orghttp://list.coin-or.org/mailman/listinfo/cbc
>
>
>
> _______________________________________________
> Cbc mailing list
> Cbc at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/cbc
>
>


-- 
Matthew Gidden
Ph.D. Candidate, Nuclear Engineering
The University of Wisconsin -- Madison
Ph. 225.892.3192
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.coin-or.org/pipermail/cbc/attachments/20140730/15a03cdc/attachment.html>