[Coin-bcpdiscuss] Information on the children of a node

[Laszlo Ladanyi]

Francois' suggestion is one way to do it, and another way is to use info
directly from the branching variables. In initialize_new_search_tree_node()
vars[i]->is_non_removable() is true iff the variable is has been branched on.
This gives you which pattern to exclude. 

In fact, we have a paper about how BCP can be used for rapid prototyping of
algorithms (http://www.springerlink.com/content/w6645815gp163275/), and the
example we used was the cutting stock problem with branch and price :-).  
It's not a terribly fast code; there's no good preprocessing specific to the
cutting stock problem, no good heuristic, but it does show how bcp can be
used.  

The code was on cvs, but I haven't ported it to the svn repository yet. If
you'd like, sometime next week I can move the code to svn and make sure that
it compiles and runs. Then you can extend it any way you like. And if yo ufeel
like you can contribute the changes back to make it a better code :-).

--Laci

On Sun, 28 Jan 2007 fmargot at andrew.cmu.edu wrote:

> 
> Sumitra:
> 
> One way to do this is to use BCP_user_data. When the sons are created,
> put a flag in a BCP_user_data object to identify which is which. This
> is described in bac.pdf (although not for column generation) 
> that you can find in the subdirectory Bcp/examples/BAC of your
> installation directory.
> 
> Francois
> 
> 
> On Sun, 28 Jan 2007, Soumitra Pal wrote:
> 
> > Hi,
> >
> > I am trying to implement the branching strategy used by "P.H. Vance. 
> > Branch-and-Price Algorithms for the One-Dimensional Cutting Stock Problem, 
> > Computational Optimization and Applications, 9(3):211?228, 1998." for solving 
> > the cutting stock problem. The problem is solved using column generation.
> >
> > According to the strategy, on one branch the solver to the subproblem should 
> > not generate one particular pattern (or column). So, I need to identify the 
> > node in the BCP_user_lp::initialize_new_search_tree_node() function. This 
> > should be easy if I could store the indices of the two children created in 
> > the BCP_user_lp::set_actions_for_children() function and check the index in 
> > the initialize_new_search_tree_node() function. However, I cant see how to do 
> > this. It will be great if somebody explains this.
> >
> > Also, I will be thankful if you explain me the term "phase" as returned by 
> > the function current_phase() in the BCP parlance.
> >
> > Thanks in advance,
> > Soumitra.
> >
> >
> >
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