[Soplex] Bug in Soplex / Exact mode

[Sebastian Junges]

Hi Leon,

Since the mail didnt go through earlier and I had seen that a previous email was referred to github, 
I posted my bug on github:  https://github.com/scipopt/soplex/issues/7

There you can also find the attached file.

The other solver was the Satisfiability-Modulo-Theories checker z3:  https://github.com/Z3Prover/z3/wiki

Sebastian





> On 18 Oct 2022, at 09:03, Leon Eifler <eifler at zib.de> wrote:
> 
> Hi Sebastian,
> 
> sorry this took a while to get to. Can you send the lp file that led to this error so I can look if anything can be done? (the debug.lp that you attached is not something I can read with SoPlex).
> 
> Out of interest: Which other exact solver did you use to produce this result?
> 
> Best,
> 
> Leon
> 
> Am 9/15/2022 um 12:58 PM schrieb Sebastian Junges:
>> Dear developers,
>> 
>> with great interest and quite some success, we have investigated SoPlex as a backend for our probabilistic model checker. Many thanks for your continued development of this LP solver.
>> 
>> During one of the tests, we encountered an error message which can be reproduced from the command line using
>> 
>> soplex --readmode=1 --solvemode=1 -f0 -o0 debug.lp
>> 
>> Error while testing for infeasibility.
>> 
>> SoPlex status       : error [unspecified]
>> Solving time (sec)  : 0.15
>> Iterations          : 3752
>> Objective value     : 0.00000000e+00
>> 
>> I attached the problem description and the full output. 
>> 
>> Using another exact LP solver, the objective value should be 3378681/200000000000000 (approx. 1.6893405e-08). 
>> I understand that the problem is numerically challenging, which is why using an exact solver is intereting for us.
>> 
>> Please let me know if you need any other information.
>> 
>> Best,
>> Sebastian Junges
>> 
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