[Cbc] What does "bad ub change for column 35 from 3 to 7" mean?

[John Forrest]

I am tracking this down and think I can see problem.  Will try and fix
in trunk.

John Forrest
On Fri, 2011-03-25 at 14:20 +0100, Kim Hansen wrote:
> Hi,
> 
> (I have send this yesterday, but the first message appears to have been lost).
> 
> I have a MIP problem that cbc has a problem with:
>  http://ange.dk/~kim/bad_ub.mps.gz
> 
> It prints a lot of errors like this:
> Cbc0010I After 4000 nodes, 229 on tree, 35778 best solution, best
> possible 32038.1 (330.41 seconds)
> bad ub change for column 35 from 3 to 7
> bad ub change for column 40 from 2 to 3
> bad lb change for column 49 from 1 to -0
> bad ub change for column 35 from 6 to 7
> 
> What does it mean and what can I do to avoid it?
> 
> I have the problem with the cbc 2.5.0, it is the version that is in
> Debian Squeeze. When I use the older cbc 2.20.00 from CoinAll 1.2.0 it
> does not have the problem. Actually it solves the problem with the old
> solver in about 5 seconds while the new version uses 850 seconds.
> 
> Regards,