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

[Xypron]

Hello Brady, hello Andrew,

the graphs created by BAK seem very useful for understanding
the dynamics of the MIP solution process. Hence a stable integration
with GLPK makes sense.

I guess it would be useful to separate the changes to GLPK into
- a hook function providing the necessary information
- an implementation of the hook function writing the bak-file
- an executable interpreting the BAK specific command line arguments
and then calling glp_main(argc, argv)

The hook function implementation and the executable
might also be merged into glpsol.

The hook function would allow to integrate the analysis into a GUI
enabled tool using the GLPK library.

The hook function could be defined in structure glp_iocp
like the existing callback function.

Best regards

Xypron


Brady Hunsaker wrote:
> 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.
>
> Brady
>
>
> Andrew Makhorin wrote:
> > > Well, there is any way to obtain the entire list of nodes and build
> > > the tree?
> >
> > Currently such a feature is not supported.
> >
> > > Is possible to modify the B C api #39;s to obtain that list?
> >
> > In principle, yes. You can trace each new node of the tree in the
> > the callback routine specifying it in the parameter list passed to
> > glp_intopt. For more details please see the glpk reference manual
> > included in the distribution.
> >
> > Another way is to patch the glpk source code (see the routine
> > ios_driver in file src/glpios03.c). See also the BAK package
> > developed by Brady Hunsaker, which allows visualizing the search
> > tree for three mip solvers including glpk:
> > http://www.rosemaryroad.org/brady/software/index.html
> >
> >
> >
> > _______________________________________________
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> > address@hidden
> > http://lists.gnu.org/mailman/listinfo/help-glpk
>
>
>
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