[Coin-bcpdiscuss] Custom branching

[Matteo Salani]

Hello!

I would like to ask for some hints and suggestions for implementing a 
custom branching scheme within Coin-BCP
I'm implementing a B&P algorithm for a heterogeneous fleet VRP-like 
problem using the BCP framework.

I've implemened the root node, the var generator and other functions 
quite easily.
Thus, so far I've an optimization based heuristic where the root node is 
solved to optimality and the default BCP's branching scheme is invoked 
to find an integral solution when no additional columns can be generated.

I would like to branch on the vehicle-customer affectation first and 
then on arcs.
In this kind of branching schemes one branching decision would affect 
the bounds of several variables.
Can I just modify the bounds or should I take care of columns removal 
from the LP?
Should I keep the already generated variables in a column pool for using 
them in other tree nodes?
Are those columns automatically re-inserted in the formulation as soon 
as i restore the bounds (for instance in other search tree nodes)?

I'm looking at the MCF-3 example from the Coin-Bcp package, in 
particular to the select_branching_candidates function. But I'm 
wondering wether this is the right way to implement a customized 
branching scheme or not. Could you please give me some pointers or hints 
on the custom branching phase?

Before digging in to the code I was searching for useful documents but 
the only thing I found are the slides of the Dimacs workshop 
(bcp_tutorial) by Prof. Margot and Prof. Ladanyi. On the other available 
documents it seems to me that only standard branching schemes are 
implemented (with standard I mean directly on variables).

Thanks in advance,
Matteo Salani
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