[Cbc] cbc infeasible, cplex not

[John Forrest]

James,

I have checked in changes in trunk.  As there is a small overhead 
cleaning up SOS variables, the changes are on an option.  See 
cleanBounds in CbcModel.hpp for more information.

Preprocessing works for both examples.  Keep me informed on problems.

John

On 14/05/18 00:57, James Howey wrote:
>
> Attached lp comes up infeasible in cbc, but finds optimal objective in 
> cplex. In cbc I ran it with and without preprocessing which has given 
> me problems before.
>
> I ran latest trunk build and an older one. I saw one checkin in latest 
> saying SOS shouldn’t have tolerance, and wonder if this is another 
> similar manifestation.
>
> It looks like it is correctly computing l1 (63999/64000), but then 
> rounding l2 (1/64000 = 1.5625e-5) down to zero. It would seem that a 
> consistent rounding strategy would yield a feasible solution. If it 
> doesn’t admit l2 = 1.5625e-5 to the solution, it shouldn’t let l4 = 
> 1.5930576e-09 in . If it rounds l2 = 1.5625e-5 to zero, it should 
> round l1 = .99998089 to 1.0. I would prefer no tolerance.
>
> X0009905: S2:: HS_ST(0)_l1:1 HS_ST(0)_l2:2 HS_ST(0)_l3:3 HS_ST(0)_l4:4
>
> Integer infeasible - objective value 0.00000000
>
>      10 HS_ST(0)_l1 0.99998089                       0
>
>      11 HS_ST(0)_l2                0                       0
>
>      12 HS_ST(0)_l3 1.9106687e-05                       0
>
>      13 HS_ST(0)_l4 1.5930576e-09                       0
>
> In the meantime, can anyone suggest a workaround?
>
> Thanks,
>
> jkh
>
>
>
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