Re: [Help-glpk] Branch and cut tree representation.

[Andrew Makhorin]

Hi Brady,

> Thanks, Andrew, for remembering BAK.  I need to update the page you 
> referenced.  Up-to-date access to BAK is here:
> http://www.rosemaryroad.org/projects/BAK/

> I have been meaning to let this list know about BAK and what we're 
> doing.  There is a patch that you apply to the GLPK source code 
> (included in the BAK download) that allows us to collect the data we 
> need.  BAK is written in Python and Gnuplot (Python is a change from 
> earlier versions) and allows the creation of several tree and progress
> visualizations with minimal overhead.  The link above includes a manual
> that shows some of what you can create with BAK.

> I would love to get feedback from people who try BAK out.

> Andrew, I'm going to follow up with you to see if it is possible to 
> incorporate the changes to GLPK directly into GLPK.

I agree with Xypron and think that having such feature in glpk would
be useful.

It is quite easy to make necessary changes in glp_intopt to collect
all necessary information. However, one question has to be resolved:
where to store the information? It can be stored either in the memory
(in which case even the glp_graph data structure could be used to
represent the tree), or in a text file, say, in a DIMACS-like format.
I would choose the latter case, because the tree inspection is a kind
of post-optimal analysis; in this case the filename could be passed to
glp_intopt via the glp_iocp parameter block.

Best regards,

Andrew Makhorin