[Coin-discuss] Mistaken infeasibility when using reduce-and-split cut generator

[fmargot at andrew.cmu.edu]

Esben:

Do you have an up-to-date copy of Cbc/trunk? For me, both

cbc mistaken_infeasibility_447.mps -solve
cbc mistaken_infeasibility_447.mps -reduce root -solve

give the correct answer. In the future, please post cbc related question
to the cbc mailing list cbc at list.coin-or.org.

Francois



On Mon, 4 Jun 2007, Esben Mose Hansen wrote:

> Hi,
>
> I came across this problem: For both /devel and /trunk branches, running with
> reduce-and-split active, even at root, makes coin believe the problem is
> infeasible.  A short select  from the output is included below, while the
> problem itself is available at
>
> http://ange.dk/public/mistaken_infeasibility_447.mps
>
> it's about 1000 variables.
>
> The output:
>
> $ cbc mistaken_infeasibility_447.mps -reduce off -solve
> [...]
> Cbc0013I At root node, 37 cuts changed objective from 341649 to 1.21167e+06 in
> 17 passes
> [...]
> Result - Finished objective 1.21174e+06 after 2 nodes and 684 iterations -
> took 1.34008 seconds
>
> $ cbc mistaken_infeasibility_447.mps -reduce root -solve
> [...]
> Cbc0013I At root node, 298 cuts changed objective from 341649 to 593399 in 1
> passes
> [...]
> Result - Finished objective 1e+50 after 0 nodes and 243 iterations - took
> 0.760047 seconds
>
> What is going on here?
>
>