[Coin-bcpdiscuss] Variable LB fixed to 1 by BCP

[Matteo Salani]

Hi all!

I've encountered a behavior of BCP that sounds strange to me...

I'm solving a set covering like problem with BCP.
At iteration 12 the lower bound of one variable becomes 1 unless the 
column generation process is not over (I've in total 149 iterations)
it sounds very strange to me that such fixing can occur at this point.

to see that I've added in the derived method 
App_lp::modify_lp_parameters which is called *before* the LP is solved
the following piece of code to write the current LP to a file:
    sprintf( fname, "lp-out%d", count++);
    lp->writeLp( fname, "lp");

count is just a static counter to have a file per iteration.

I've checked that in all the code I do not modify any variable bound.

What else should I check?
Is BCP acting on variables' LBs?

Am I right when I say that reduced cost fixing could act only on 
variables' upper bounds?

Thanks,
Matteo
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